Category Archives: Beary Scientist

Sputnik 60th Anniversary

It had antennae and it went round and round!

Sixty years ago, Sputnik became the first satellite in space and changed the world forever. Its polished surfaces and distinctive antennae are now unmistakable.

Launched by the Soviet Union on October 4, 1957, this shiny orb kick-started the space race and opened up the heavens for mankind to explore.

The world’s first artificial satellite was about the size of a beach ball (58 cm in diameter), weighed only 83.6 kg, and took about 98 minutes to orbit the Earth on its elliptical path.

The first satellite was designed to be simple and effective. It had no scientific equipment, just batteries, a thermal regulation system and a transmission module. The decision to keep it simple meant the Russian engineers could race to launch first, beating the United States. As soon as Sputnik was launched it began orbiting the world every 98 minutes.

A single watt of power transmitted its distinctive “beep, beep, beep” as it flew around the world, an act that effectively established “Freedom of Space” — the principle that crossing national borders in space does not violate national airspace. Sputnik’s broadcast continued for 21 days. The satellite fell out of orbit and burned up on re-entry three months after its launch, in January 1958.

The original satellite is long gone, but test models and engineering replicas, some more authentic than others, can be found in various museums and collections. The private museum of RSC Energia in Moscow is a treasure trove of pioneering space probes including one of the original Sputnik flight spares, built in 1957. RSC Energia is the Russian state company that built the world’s first satellite.

A full-scale replica of the Sputnik 1 — the first artificial satellite to be put into outer space — stored in the National Air and Space Museum in Washington

You can own your own replica is you have some spare change. A replica of the famous satellite went on sale at Bonhams in New York City as part of their Air and Space Sale on September 27, 2017. The full scale SPUTNIK-1 EMC/EMI Lab Model sold for US$ 847,500 (AU$ 1,085,065).

Replica of Sputnik satellite went on sale at Bonhams in New York City on 27 September 2017 – Sold for US$ 847,500 (AU$ 1,085,065) inc. premium

Despite its simplicity, Sputnik 1 also served science. The USSR built a network of observational stations throughout the country to track its path. Based on those observations, researchers obtained new information on the atmospheric density at Sputnik’s altitudes, and a new branch of science was conceived – space geodesy. Without any specific scientific equipment, however, Sputnik 1 was considered by many to be a mere toy sent for the sake of the space race. Its successors, Sputnik 2 and Sputnik 3, were much more scientific in their missions. On November 3, 1957, Sputnik 2 carried the dog Laika, the first living being in space. Sputnik 3 which included scientific payload, was launched on May 15, 1958.

Sputnik 3 carried 12 instruments (weighing 968 kilograms out of a total of 1,327 kilograms for the entire satellite) to study solar-charged particles, electrical and magnetic fields in space, ion content and density of the upper atmosphere, and the population of micrometeoroids. Sputnik 3 data showed that there are two radiation belts around the Earth: The inner belt consists primarily of protons, whereas the outer one has a mostly electron population. Data from Sputnik 3 supported the idea that particles precipitating from the belts were the cause of auroras and ground-level electrical discharges. From there, the picture of Earth’s space environment started to assemble. The last of the formally designated Sputnik missions, Korabl-Sputnik 5, in 1961 carried a dog, Zvezdochka, along with a realistic mannequin named Ivan Ivanovich.

Sputnik 2 and Sputnik 3 marked two sharply divergent styles of space exploration: crewed (if only with dogs) versus automatic. The first approach was more appealing to the general audience, which got them used to the idea of future colonization of space. The second strategy implied that remote-sensing techniques and special robots could fully replace human beings in space. Later, when the real hostility of the space environment was assessed, the idea of extended human space travel seemed less viable than even at the time of Yuri Gagarin—the first human in space—and the Apollo program. It is now known that humans can live and work in near-Earth space; it is less clear what tasks can be done only in space and only with human hands.

The greatest opportunity Sputnik 1 and its many descendants gave to science is the opportunity not to merely observe, but to run active experiments in interplanetary (even interstellar) space or on the surface of other planets and bodies. We are nowhere near the limit of this opportunity, and this is what gives space science its constant boost.

Over the years, the impact of Sputnik continued in the literal “sputniks” (which is Russian for satellite) that followed, in the broader development of the Soviet and Russian space programs, and ultimately in the entire program of cosmic exploration that the tiny orbiting ball initiated.

Sputnik’s legacy lives on today. Every astronaut bound for the ISS blasts off from the same Baikonur cosmodrome as Sputnik I did. And Russian space agency Roscosmos has many new projects – including the Federation deep space capsule and the new Vostochny launch pad in eastern Russia.

The launch came during the depths of the Cold War, when Dwight Eisenhower occupied the White House and America’s space interests were almost entirely focused on building rockets powerful enough to deliver nuclear warheads across intercontinental distances. NASA did not yet exist, and the notion of traveling into orbit—let alone journeying to the moon and beyond—seemed little more than science fiction.

Yet by then, visionaries had not merely dreamed of space flight but had laid the foundation for making it a reality. The mathematical and engineering breakthroughs achieved by Konstantin Tsiolkovskiy (a Russian), Hermann Oberth (a German), and Robert Goddard (an American) proved that rocketing away from Earth was entirely possible.

The launch expanded the Cold War to outer space and shook up American technological smugness. It ushered in new political, military, technological and scientific developments. While the Sputnik launch was a single event, it marked the start of the space age and the U.S.-U.S.S.R space race. And it probably helped John Kennedy get elected president in 1960.

The worldwide reaction was a mixture of awe and apprehension. The Space Age – and the Space Race – had begun. American scientists had known the launch was coming because their Soviet counterparts had told them to expect it. But to an American public that had become accustomed to their country’s growing global primacy, the orbiting of Sputnik 1 was a traumatic wake-up call that caused great anxiety.

The apprehension wasn’t caused by the satellite, but by the missile that put it into space. It was an intercontinental ballistic missile that the Soviet Union had developed, they tested it just the month before for the very first time, and for the first time in its recent history the United States felt threatened.

Soviet secrecy surrounding the project made strained Soviet resources appear to be deep, secret reserves. Sputnik’s launch marked Soviet leader Nikita Khrushchëv’s first use of rockets for propaganda purposes. It also demonstrated the capabilities of the Soviet Union’s first intercontinental ballistic missile, the R–7, which had only flown once before.

The story begins in 1952, when the International Council of Scientific Unions decided to establish July 1, 1957, to December 31, 1958, as the International Geophysical Year (IGY) because the scientists knew that the cycles of solar activity would be at a high point then. In October 1954, the council adopted a resolution calling for artificial satellites to be launched during the IGY to map the Earth’s surface.

In July 1955, the White House announced plans to launch an Earth-orbiting satellite for the IGY and solicited proposals from various Government research agencies to undertake development. In September 1955, the Naval Research Laboratory’s Vanguard proposal was chosen to represent the U.S. during the IGY.

The Sputnik launch changed everything. As a technical achievement, Sputnik caught the world’s attention and the American public off-guard. Its size was more impressive than Vanguard’s intended 1.5 kg payload. In addition, the public feared that the Soviets’ ability to launch satellites also translated into the capability to launch ballistic missiles that could carry nuclear weapons from Europe to the U.S. Then the Soviets struck again; on November 3, Sputnik II was launched, carrying a much heavier payload, including the dog Laika.

Immediately after the Sputnik I launch in October, the U.S. Defense Department responded to the political furore by approving funding for another U.S. satellite project. As a simultaneous alternative to Vanguard, Wernher von Braun and his Army Redstone Arsenal team began work on the Explorer project.

On January 31, 1958, the tide changed, when the United States successfully launched Explorer I. This satellite carried a small scientific payload that eventually discovered the magnetic radiation belts around the Earth, named after principal investigator James Van Allen. The Explorer program continued as a successful ongoing series of lightweight, scientifically useful spacecraft.

The Sputnik launch also led directly to the creation of National Aeronautics and Space Administration (NASA). In July 1958, Congress passed the National Aeronautics and Space Act (commonly called the “Space Act”), which created NASA as of October 1, 1958 from the National Advisory Committee for Aeronautics (NACA) and other government agencies.

Sputnik was the beginning of a long list of Russian firsts:

  • The first living being in space – the dog Laika onboard Sputnik II in 1957, who unfortunately did not survive the experience
  • The first man in space – Yuri Gagarin, 1961, who did survive the experience
  • The first woman in space – Valentina Tereshkova, 1963
  • The first spacewalk – by Alexey Arkhipovich Leonov, 1965
  • The first spacecraft on the moon – Luna 2, 1959
  • The first spacecraft on Venus – Venera 7, 1970
  • The first soft landing on Mars – Mars 3, 1971

However, with the American moon landings in 1969, the space race that Sputnik began started to draw to a close.

Today it’s all about cooperation, rather than competition, between Roscosmos, ESA, NASA and other space agencies.

One of the most ambitious current collaborations is ExoMars, a two-part effort between ESA and the Russian Roscosmos State Corporation for Space Activities since 2013 to search for signs of past and present life on Mars. The first ExoMars mission, launched in 2016, consisted of the Trace Gas Orbiter (TGO) and Schiaparelli lander. TGO will perform a thorough study of Martian atmospheric trace gases, which may inform us about possible ongoing biological activity. TGO is currently circling Mars and will start its scientific mission once it reaches its final orbit in April 2018. The second ExoMars mission, to be launched in 2020, comprises a European rover and a Russian stationary surface platform that will extend the studies of geochemistry and possible biochemistry to the surface. The rover bears two instruments built in Russia; the descent module to land on Mars is provided by Roscosmos, as is the Proton launcher for this mission.

Russia is also contributing several instruments to the upcoming European-Japanese BepiColombo mission to Mercury. This dual-probe spacecraft aims to analyze the interior of the smallest planet, its interaction with solar wind, and the composition of its upper surface.

In the 2020s, Roscosmos plans to participate in two major new space-plasma and solar missions. One, called Resonance, consists of several identical spacecraft that will orbit within a single “tube” of flux in Earth’s inner magnetosphere, closely monitoring interactions between particles and waves in this region. Such observations will enable new insights into space weather, which can disrupt communications and overload power lines on Earth. Interhelioprobe is a mission to send two identical spacecraft to within 45 million kilometers of the Sun, high out of the plane of the Solar System. No spacecraft has yet operated in these regions. Interhelioprobe is not expected to launch until after the end of the current Federal Space Program of the Russian Federation in 2025, however, so its future is especially sensitive to the divine laughter that often greets ambitious plans.

Old proverb: If you want to make God laugh, tell her about your plans.

More information on American Scientist.

Equinox

It’s here, it’s here!

It’s the beginning of astronomical spring! Even if it doesn’t feel like it…

We may celebrate the equinox as a day, but it’s actually just one moment. And it’s just gone! It’s really not when the day and the night are of equal length, although that’s what we think of – it’s the moment when the sun is on the equator at local noon. The equinox occurs when the sun crosses the celestial equator (an imaginary line above the Earth’s equator), and the Earth is perpendicular to the sun’s rays.

Today’s equinox is one of only two days each year when the sun can be seen directly overhead along Earth’s equator. It’s also one of only two days each year when all points on Earth — apart from the polar regions — see the sun rise due east and set due west along the horizon.

That is, today the sun rises precisely due east and sets precisely due west.

Doesn’t it do that everyday, you might ask? No. Sometimes the sun rises a bit northeast, sometimes a bit southeast, depending on the season. East and west are defined by features of the earth rather than the sun, like the positions of the North Pole and South Pole.

The celestial equator is a circle drawn around the sky, above Earth’s equator. The ecliptic is the sun’s apparent yearly path in front of the constellations of the Zodiac. The ecliptic and celestial equator intersect at the spring and autumn equinox points.

An equinox occurs when the sun crosses the celestial equator. No matter where you are on Earth, the celestial equator intersects your horizon at due east and due west.

At its highest point in your sky, the celestial equator appears high or low, depending on your latitude. The imaginary celestial equator is a great circle dividing the imaginary celestial sphere into its northern and southern hemispheres, so, from the equator, it’s directly overhead, for example, wrapping the sky directly above Earth’s equator.

For purposes of today’s visualization, though, the height of the celestial equator in your sky doesn’t matter. What matters are these two things. One, the sun is on the celestial equator at the equinox. Two, the celestial equator intersects your horizon at points due east and due west.

Voila. The sun rises due east and sets due west on the day of the equinox, as seen from around the globe.

Where does the celestial equator intersect your horizon? No matter where you are on Earth (unless you’re at a pole), the celestial equator meets your horizon at points due east and due west.
Why does the sun rises due east and set due west at the equinoxes? The blue line is the celestial equator (always at your due east and due west points). The purple line is the ecliptic, or sun’s path. At the equinox, these two lines intersect. Illustration via JCCC Astronomy.

And now we’re midway between the two extremes of the sun’s path in the sky.

The seasons result from the Earth’s rotational axis tilting 23.5 degrees out of perpendicular to the ecliptic – or Earth’s orbital plane

A few years ago the team at NASA’s Earth Observatory used observations from a EUMETSAT meteorological satellite to make the video below, which shows what the solstices and equinoxes look like from space.

It’s time to go back to sleep 🙂

Google doodle for the Southern Hemisphere spring equinox

The Science of the Northern Lights

The aurora polaris is a phenomenon that offers a unique experience to anyone who views it. It is made up of two auroral ovals: the aurora borealis, found at the North Pole, and the aurora australis, found at the South Pole. Appearing as a shimmering curtain of light in the night sky, it has amazed and astounded mankind for thousands of years. Many tales of the magical and supernatural have emerged over time, each attempting to explain the phenomenon, but only relatively recently have scientists developed an understanding of the aurora.

An understanding of the aurora first requires an understanding of the Sun and of our planet, as well as some of the fundamentals of physics.

At the centre of our solar system is the Sun: a huge ball of super-heated gas, or plasma, which accounts for over 99 percent of the total mass of the entire solar system. The gas in question is hydrogen, the lightest and most abundant element in the universe. Within every star, including our Sun, this gas is constantly undergoing nuclear fusion. This is a process whereby the hydrogen is converted into helium gas, the second most abundant and second lightest element in the universe, by means of a nuclear reaction which is responsible for the production of all the energy radiated by the Sun. It provides all of the light, heat and energy necessary for life on Earth. Despite its relatively calm appearance when viewed from Earth with the naked eye, our star is an extremely complex, dynamic and active object and it is this activity that causes the Northern Lights, the aurora borealis.

A section of the eleven year cycle of the Sun, between 1996 and 2006. NASA

The Sun has an eleven-year cycle of activity, which peaks and troughs regularly, and which is responsible for what is known as space weather. At the beginning of the cycle, activity on the SUn is high, a state known as solar maximum; this takes approximately five and a half years to peak. After this, activity on the Sun decreases, to solar minimum, reaching the trough where activity is at its lowest point after another five and a half years, before it returns, once again, to the beginning of the cycle and solar maximum. At its minimum level of activity the Sun is still dynamic, but, in comparison to solar maximum, this is considered to be calm space weather.

The activity associated with the solar cycle manifests itself in several ways. Observations of the Sun have revealed three of the principal types of activity to be sunspots, solar flares and coronal mass ejections. Sunspots are dark spots on the photosphere, the outer shell of the Sun from which light radiates, which are cooler than the surrounding area and therefore appear darker in colour. These are temporary phenomena which are caused by intense magnetic activity, and generally appear in pairs.

Three images of the Sun showing increasing sunspot activity. NASA

Solar flares occur when plasma erupts and is flung upwards, after which it rains back down on the Sun. A coronal mass ejection (CME) is very similar to a solar flare and occurs when the erupting plasma has enough energy to break free from the Sun and travel into space. These ejections are incredibly energetic and travel at a very rapid rate, which is necessary for the material to overcome the gravitational pull of the Sun and achieve what is known as escape velocity. This is the speed at which an object or objects must travel in order to escape permanently the gravity of another object in space. This speed is variable and is calculated based upon the mass of the object that is to be escaped from. The more massive the object is, the greater the gravitational pull and thus its escape velocity.

A coronal mass ejection (CME). NASA

In addition to these phenomena, the Sun also produces ‘solar wind’. This is not wind as we understand it on Earth, generated by the flow of warm and cold air around the planet. The solar wind is a stellar wind, produced by the stars and it consists of charged particles which stream outwards from the Sun in every direction, travelling at approximately 1.5 million kilometres per hour. All stars produce wind of this type and they do so to varying degrees of intensity.

The heliosphere is a huge ‘bubble’ that is blown by the Sun by means of the solar wind, and it is within this bubble that the solar system resides. The farther form the Sun the solar win travels, the weaker the influence of the Sun becomes, and eventually it approaches a boundary known as the termination shock. This is the point at which the particles of the solar wind are travelling at subsonic speeds, or slower than the speed of sound. There is a second, more distant boundary known as the heliopause. The heliopause is the point at which the pressure of the solar wind pushing outward from the Sun is equal to the pressure exerted by the interstellar medium, that is the material in space between the stars, and the stellar winds produced by other stars close by. This is the edge of the bubble. The area between the termination shock and the heliopause is known as the heliosheath. Because the Sun is travelling through space, taking with it the solar system, a wave forms in front of it as it travels, and this is called the bow shock.

A diagram of the heliopause. NASA/JPL

This can be visualised by imagining a boat travelling through water. As it does so it creates a wave that goes before it. In recent years, NASA has collected new data which contradict this theory, suggesting there may be no bow shock at all. The heliosphere is so large that the Voyager spacecraft launched in 1977 are only now reaching the threshold between the heliosphere and interstellar space. NASA is attempting to explore this region with the Interstellar Boundary Explorer mission, or IBEX, which examines the nature of the interactions between the solar wind and the interstellar medium at the edge of our solar system.

CMEs, or solar flares and the solar wind are the causes of the aurora, and the significance of a solar maximum is that it causes more and greater interactions between Earth and the Sun, and therefore auroras which are viewed during a solar maximum are usually more spectacular, energetic, and ultimately, more beautiful.

The interaction between the Earth and the Sun is responsible for the aurora borealis. Earth generates an invisible magnetic bubble, or magnetic field, called the magnetosphere. This magnetic bubble encloses the planet in a protective shield, preventing us from being subjected to an array of toxic sources, such as radiation from the Sun or from other sources, such as cosmic rays. The Sun produces vast amounts of radiation which is hazardous to life, in particular ultraviolet light, although some of this does manage to get through the magnetosphere: if you are exposed to it you will, depending upon your skin complexion, receive either a sun tan or sun burn.

Earth’s magnetosphere deflects most charged particles away from Earth – but some do become trapped in the magnetic field and create auroras when they rain down into the atmosphere. NASA has several missions that study Earth’s magnetosphere – including the Magnetospheric Multiscale mission, Van Allen Probes, and Time History of Events and Macroscale Interactions during Substorms (also known as THEMIS) – along with a host of other satellites that study other aspects of the Sun-Earth connection.

NASA
NASA

The magnetosphere is generated deep inside the Earth, in the core of the planet. Composed mostly of nickel and iron, the core has two separate and distinct parts. The inner core is solid and the outer core is molten, and therefore very hot. The rotation of the Earth has the effect of producing convection currents in this molten metal. Convection is the transfer of heat within a material where the material itself does not move as a whole; thus, the heat in the hotter parts of the liquid metal core is moving to the cooler areas, and the currents produced by this transfer of heat generate the magnetic field of the magnetosphere. This is sometimes referred to as the Dynamo Effect. The magnetosphere is active and energetic. Magnetite deposits on Earth shows us that it ‘flips’ every so often, so that the poles change over, reversing the polarity of the magnetosphere. The next time the polarity flips it will cause the compasses to point south rather than north. There is nothing in the millions of years of geologic record to suggest that any of the doomsday scenarios connected to a pole reversal should be taken seriously. A reversal might, however, be good business for magnetic compass manufacturers. The conditions that cause polarity reversals are not entirely predictable, but the science shows that magnetic pole reversal is – in terms of geologic time scales – a common occurrence that happens gradually over millennia. Reversals take a few thousand years to complete, and during that time the magnetic field does not vanish. It does get more complicated.

A schematic diagram of Earth’s interior. The outer core is the source of the geomagnetic field. NASA
Supercomputer models of Earth’s magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is the sort of complicated magnetic field Earth has during the upheaval of a reversal. NASA
Earth’s magnetosphere as it would look if we had “magnetic field glasses”. The shape is created by the interaction of the solar wind with Earth’s intrinsic magnetic field. NASA

The magnetosphere is an invisible magnetic field that emanates from the poles. This is not true of all the planets. Mars, for example, has lost almost all of its magnetic field over time because its core has solidified, making it not only an aurora-free world (that settles it, we’re not moving there!), but also causing the surface of the red planet to be much more susceptible to the ravages of solar and cosmic radiation. Contrastingly, Jupiter, the largest planet in our solar system, generates a huge magnetic field. This is far greater in strength and intensity than Earth’s magnetic field, and would be extremely toxic to humans due to its ability to generate powerful radiation belts by trapping and accelerating radioactive particles. The core of Jupiter is made of hydrogen, which ordinarily is not able to produce electricity or magnetism. In this case, however, the enormous weight of Jupiter’s upper atmosphere subjects the hydrogen in the core to pressure equivalent to millions of times that of the atmospheric pressure on Earth, and under these conditions hydrogen is thought to enter an exotic state and become metallic, and is subsequently able to conduct electricity. This process is thought to account for the magnetic field that is generated around Jupiter.

Hubble Captures Vivid Auroras in Jupiter’s Atmosphere. NASA
Blue aurora on Jupiter. NASA/J Clarke

Given the variations we observe in our own solar system, it is clear that we reside in a sort of magnetic oasis, a ‘sweet spot’ where the conditions are safe enough to protect us from harmful radiation produced by our star, but also interesting and energetic enough to allow us to observe one of the greatest wonders of the world, the aurora borealis.

Aurora Borealis, northern Norway

The interaction between the Earth’s magnetism and electrically charged particles from the Sun is what creates the aurora borealis. The charged particles of the solar wind, electrons, stream towards Earth and collide with the gases in the Earth’s atmosphere, made up mainly of nitrogen and oxygen. In the process of colliding, the electrons deliver energy to the magnetosphere and the energy is temporarily stored there as electrical currents and electromagnetic energy. This is not a stable state for the magnetosphere, however, and the energy is prone to sudden release. When this happens, the energy accelerates electrons in the magnetosphere and they are funnelled down towards the poles where they collide with gas atoms in the atmosphere. This in turn excites the atoms, causing them to become more energetic. The atoms of gas in the atmosphere consist of an atomic nucleus, the centre of an atom and a cloud of electrons which orbit the nucleus. In order for an atom to become excited the electrons must be pushed farther away from the nucleus. This is a higher energy orbit. The atoms do not retain this energy indefinitely and remain this way, however, and so they must undergo the process of returning to their previous state and that means that the electrons return to a lower energy orbit, closer to the nucleus. The energy that the atoms gain from the solar wind must go somewhere, for energy cannot be destroyed or simply disappear; it can only be converted into other forms of energy. It must obey the laws of physics. In the case of the aurora borealis, the energy is released again, this time in the form of photons, or light. It is this light that we see shimmering in the skies as aurora borealis. The more energetic the Sun, the more energy is delivered to, and subsequently released by, the atoms in the atmosphere, and the more light is produced. The more light is produced, the more spectacular the aurora that is observed.

NASA

Typically auroras are observed in several different colours. By far the most commonly observed is green, with red, blue, pink, white and purple appearing rarely. Different coloured auroras are observed because of the different gases that are producing them. Green auroras are produced by oxygen at lower altitudes. Oxygen at higher altitudes typically produces red, while nitrogen produces blue, often observed as purple due to atmospheric conditions and other light mixing. This mixing of light from auroras can also produce pink or white auroras.

Southern lights seen in the skies above Dunedin, New Zealand (Paul Le Comte)

The Grand Tour of The Voyager Spacecraft

The two Voyager spacecraft have taken well over 100,000 images of the outer planets, rings, and satellites, as well as millions of magnetic, chemical spectra, and radiation measurements. All this with an eight track tape deck to record data and 256kB of memory! They have collected significant new knowledge and data: Voyager 2 sent back the first images of Uranus and Neptune. The probe found 11 new moons, and a significant magnetic field around Uranus. They have improved our understanding of the characteristics of the atmosphere of Jupiter, Voyager 2 discovering that Jupiter’s Red Spot was actually a large storm in the planet’s atmosphere. They also discovered the first active volcanoes beyond Earth at Jupiter’s moon Io; hints of a subsurface ocean on Jupiter’s moon Europa; encountered Saturn’s largest moon Titan, where data showed a thick Earth-like atmosphere; found the icy moon Miranda at Uranus and spotted icy-cold geysers on Neptune’s moon Triton.

NASA/JPL poster

The significance of both Voyager spacecraft is the vast amount of new knowledge of outer space they have provided and the interest in further exploration they have generated. That interest has resulted in the Galileo mission to Jupiter and the Cassini mission to Saturn, as well as the discovery of three new moons around Saturn using Earth-based instruments.

Built to last 5 years, both Voyager spacecraft are still in space, 40 years later, exploring what lies outside our solar system.

NASA/JPL poster

The identical space crafts launched a couple of weeks apart from one another. Timed to take advantage of a favourable alignment of the outer planets not expected to recur for another 175 years, Voyager 2 launched first on August 20, 1977, followed by Voyager 1 on September 5. Although launched second, Voyager 1 was sent on a faster trajectory and was timed to arrive at Jupiter ahead of Voyager 2. This geometric lineup made possible in a single flight close-up observation of all the planets in the outer solar system (with the exception of Pluto). This planetary alignment offered a crucial advantage: As the spacecraft passed each planet, gravity would bend its flight path and increase its velocity enough to deliver it to the next destination. Known as “gravity assist”, this complex process gave the spacecraft a “slingshot” boost at each planet. Neptune, the outermost planet in the mission, thus could be reached in 12 rather than 30 years.

At each planetary encounter – running on power equivalent to the light bulb in a refrigerator – the Voyagers would transmit photographs and scientific data back to Earth before being accelerated towards their next target by the planet’s gravity, like a slingshot.

According to NASA, few missions can match the many achievements of the Voyager space crafts during their 40-year journey. Voyager 1 became the first spacecraft and only human-made object to have entered interstellar space, and Voyager 2 is expected to cross over in the next few years. Voyager 2 is the only spacecraft to have flown by Jupiter, Saturn, Uranus and Neptune.

NASA/JPL poster
Voyager 2 launches aboard Titan-Centaur III expendable rocket. NASA/JPL

When Voyager 1 arrived at Jupiter in 1979 the mission’s scientific discoveries began.

The world watched as the Voyagers’ cameras sent back – via the tracking stations – close up images of Jupiter and its moons, letting us see these worlds in detail for the very first time.

From the turbulence surrounding huge storms on Jupiter, to a volcano erupting on Jupiter’s moon Io, to hints that the icy surface of Europa probably conceals an ocean underneath, the Voyager mission started to reveal the outer Solar System to us in inspiring detail.

Getting close to Jupiter. NASA/JPL
Peering into Jupiter’s famous red spot. NASA/JPL
Voyager 1 captures a volcanic eruption on Jupiter’s moon Io. NASA/JPL
Voyager 1 image of Ganymede, Jupiter’s largest moon and the largest moon in the Solar System at 5,262km in diameter (compared to Earth’s Moon at 3,475km diameter). NASA/JPL/Image processed by Bjӧrn Jόnsson

After Jupiter, both Voyagers went on to encounter Saturn. Voyager 1 achieved the major goal of closely approaching Saturn’s giant moon, Titan.

Both Voyagers passed by the ringed planet Saturn. NASA/JPL
Layers of haze covering Saturn’s moon Titan are seen in this image taken by Voyager 1 on November 12, 1980, at a range of 22,000 kilometers. This false color image shows the details of the haze that covers Titan. The upper level of the thick aerosol above the moon’s limb appears orange. NASA/JPL

Following this encounter, with its primary mission ended, Voyager 1 was flung on a northward trajectory above the plain of the orbits of the planets. Voyager 2 was subsequently targeted to travel outward on an extended mission to visit the next two gas giant worlds.

When Voyager 2 flew past Uranus in January 1986, the signals being received were much weaker than when it flew by Saturn, five years earlier.

Voyager 2 captures Uranus. NASA/JPL

Consequently, CSIRO’s radio telescope at Parkes was linked, or arrayed, with NASA’s dishes in Canberra to boost Voyager 2’s weak radio signal.

This was the first time an array of telescopes had been used to track a spacecraft. Yet this array would be insufficient to receive the even fainter signals expected when Voyager 2 reached Neptune in 1989. So in the time between the encounters, NASA expanded Canberra’s largest dish from 64 metres to 70 metres in diameter to increase its sensitivity, and then linked it again with the Parkes 64 metre dish, to maximise the data capture at Neptune.

Neptune’s bright wispy cirrus-type clouds can been seen against the blue atmosphere. NASA/JPL/ Image processed by Bjӧrn Jόnsson

The increased size and sensitivity of the Canberra dish also meant that it was able to support Voyager’s ongoing journey beyond the outer planets.

In 1990 Voyager 1 turned its cameras towards home. The resulting photograph, known as the Pale Blue Dot, is our most distant view of Earth, a fraction of a pixel floating in a deep black sea.

“The Pale Blue” dot. The rays of light are artifacts on the photo from the Sun. NASA

The last imaging sequence was Voyager 1’s portrait of most of the solar system, showing Earth and six other planets as sparks in a dark sky lit by a single bright star, the Sun.

Solar System Portrait – Views of 6 Planets – Left to right and top to bottom: Venus, Earth, Jupiter, and Saturn, Uranus, Neptune. NASA/JPL

In the first decade of the 21st century Voyager 1 continued to provide important scientific data about the heliopause, the outer limits of the Sun’s magnetic field and outward flow of the solar wind.

The Canberra tracking station continues to receive signals from both Voyager spacecraft every day, and is currently the only tracking station capable of exchanging signals with Voyager 2, owing to the spacecraft’s position as it heads on its southward path out of the Solar System.

The Parkes telescope tracking Voyager 2 at Neptune on the day of the close approach. CSIRO

Due to their respective distances, tens of billions of kilometres from Earth, the signal strength from both spacecraft is very weak, only one-tenth of a billion-trillionth of a watt.

In August 2012, Voyager 1 became the first spacecraft to have entered interstellar space (detected by a plasma wave instrument), the region between the stars. Voyager 2 is expected to follow in the next few years. Lying beyond the influence of the magnetic bubble generated by our Sun, Voyager 1 is able to directly study the composition of the interstellar medium, for the first time.

Voyager 1 is still receiving commands that can only be sent from Canberra’s dishes. It is the only station with the high-power transmitter that can transmit a signal strong enough to be received by the spacecraft.

It has been an epic voyage for two spacecraft no bigger than small buses, two brilliant robots with an eight track tape deck to record data and 256kB of memory! However, all the Voyager instruments (TV cameras, ultraviolet and infrared spectrometers, photopolarimeter) can be pointed with an accuracy of better than one-tenth of a degree. Each spacecraft contains a Golden Record, a phonographic gold-plated copper capsule containing Earth sounds, pictures and messages designed to give any possible alien who encounters the spacecraft an idea of what life on Earth is like. They are expected to last billions of years and could one day be the only traces of human civilization.

NASA/JPL poster – Homage to the Voyager mission greatest hits

By 2030, both Voyagers will be out of power, their scientific instruments deactivated, no longer able to exchange signals with Earth. They will continue on at their current speeds of more than 17 kilometres per second, carrying their golden records like messages in bottles across the vast ocean of interstellar space.

Heading in opposite directions, southward and northward out of the Solar System, it is expected that in about 40,000 years, Voyager 1 will come within 1.7 light years of star AC+793888 in the constellation Ursa Minor (the Little Bear) and Voyager 2 will come within about 1.7 light years of a star called Ross 248, a small star in the constellation of Andromeda. Before then, in about 300 years, Voyager 1 will reach our solar system’s Oort Cloud of comets. It will be 296,000 years before Voyager 1 passes by the bright star Sirius!

Beyond that, we may imagine them surviving for billions of years as the only traces of a civilisation of human explorers in the far reaches of our galaxy.

Little Puffles and Honey saw the model of the Voyager spacecraft at the Smithsonian National Air and Space Museum.

Development Test Model (DTM) for the Voyager spacecraft, on display in the Exploring the Planets gallery, Smithsonian National Air and Space Museum

This artefact is a Development Test Model (DTM) for the Voyager spacecraft that consists of facsimile and dummy parts manufactured by the Jet Propulsion Laboratory. It was acquired by NASM in 1977 and placed on display in the Exploring the Planets gallery shortly thereafter.

Voyager was the little spacecraft that could. – Edward Stone, Voyager Chief Scientist, Jet Propulsion Laboratory

Artist’s concept of Voyager in flight. NASA/JPL

Original article in The Conversation.

Sounds, Pictures & Messages From A Pale Blue Dot

In 1977, a pair of phonograph records containing recordings of life on Earth were launched aboard the twin Voyager space probes.

In 1977, NASA sent a collection of music, sounds, and images from Earth into outer space.

The creation of the Golden Record was overseen by Carl Sagan. Frank Drake, Ann Druyan, Linda Salzman Sagan, Jon Lomberg, Timothy Ferris, Jimmy Iovine, all contributed to the record. John Lennon’s trick of etching little messages into the blank spaces between the takeout grooves at the ends of his records inspired Timothy Ferris to do the same on Voyager, and the dedication “To the makers of music—all worlds, all times” was inscribed on the records.

To the team’s surprise, those nine words created a problem at NASA. An agency compliance officer, charged with making sure each of the probes’ sixty-five thousand parts were up to spec, reported that while everything else checked out — the records’ size, weight, composition and magnetic properties — there was nothing in the blueprints about an inscription. The records were rejected, and NASA prepared to substitute blank discs in their place. Only after Carl Sagan appealed to the NASA administrator, arguing that the inscription would be the sole example of human handwriting aboard, was permission given for the records to fly.

In selecting Western classical music, the team sacrificed a measure of diversity to include three compositions — one by J. S. Bach and two by Ludwig van Beethoven. The team made an allowance for extraterrestrials who lacked what we would call hearing, or whose hearing operated in a different frequency range than ours, or who hadn’t any musical tradition at all. Even they could learn from the music by applying mathematics, which really does seem to be the universal language that music is sometimes said to be. They’d look for symmetries — repetitions, inversions, mirror images, and other self-similarities — within or between compositions. The team sought to facilitate the process by proffering Bach, whose works are full of symmetry, and Beethoven, who championed Bach’s music and borrowed from it.

Blind Willie Johnson’s “Dark Was the Night” Chuck Berry’s “Johnny B. Goode” were also included, along with a sequence of natural sounds, organized chronologically. The sequence begins with an audio realization of the “music of the spheres”, in which the constantly changing orbital velocities of Mercury, Venus, Earth, Mars, and Jupiter are translated into sound, using equations derived by the astronomer Johannes Kepler in the 16th century. Then there are the sounds of volcanoes, earthquakes, thunderstorms and bubbling mud of the early Earth. Wind, rain, and surf announce the advent of oceans, followed by living creatures — crickets, frogs, birds, chimpanzees, wolves — and the footsteps, heartbeats, and laughter of early humans. Sounds of fire, speech, tools, and the calls of wild dogs mark important steps in our species’ advancement, and Morse code announces the dawn of modern communications. (The message being transmitted is Ad astra per aspera, “To the stars through hard work.”) A brief sequence on modes of transportation runs from ships to jet airplanes to the launch of a Saturn V rocket. The final sounds begin with a kiss, then a mother and child, then an EEG recording of (Ann Druyan’s) brainwaves, and, finally, a pulsar — a rapidly spinning neutron star giving off radio noise — in a tip of the hat to the pulsar map etched into the records’ protective cases. There is also a collection of loquacious greetings from United Nations representatives, edited down and cross-faded to make them more listenable 🙂 with beautiful recordings of whale songs mixed in.

The team involved in making the Golden Record assumed that it would soon be commercially released, but that didn’t happen. Carl Sagan repeatedly tried to get labels interested in the project, only to run afoul of what he termed, in a letter dated September 6, 1990, “internecine warfare in the record industry”. As a result, nobody heard the thing properly for nearly four decades. Now it is available from Ozma Records.

Carl Sagan, who was a member of the Voyager mission imaging team, gave us another present in 199, an incredible perspective on our home planet that had never been seen before.

As Voyager 1 was about to leave our Solar System in 1989, Sagan pleaded with officials to turn the camera around to take one last look back at Earth before the spaceship left our solar system.

The resulting image, with the Earth as a speck less than 0.12 pixels in size, became known as “the pale blue dot”.

“The Pale Blue” dot. The rays of light are artifacts on the photo from the Sun.NASA

Astronauts had already taken plenty of beautiful photos of our planet at that point, and this grainy, low-resolution snapshot was not one of them. But instead of beauty, this one-of-a-kind picture showed the immeasurable vastness of space, and our undeniably small place within it.

Sagan would later write about the photograph — and the deeper meaning he gleaned from it — in his 1994 book, Pale Blue Dot: A Vision of the Human Future in Space.

Here’s what he wrote:

From this distant vantage point, the Earth might not seem of any particular interest. But for us, it’s different. Consider again that dot. That’s here. That’s home. That’s us.

On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.

The aggregate of our joy and suffering, thousands of confident religions, ideologies, and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilization, every king and peasant, every young couple in love, every mother and father, hopeful child, inventor and explorer, every teacher of morals, every corrupt politician, every ‘superstar,’ every ‘supreme leader,’ every saint and sinner in the history of our species lived there – on a mote of dust suspended in a sunbeam.

The Earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner.

How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light.

Our planet is a lonely speck in the great enveloping cosmic dark.

In our obscurity – in all this vastness – there is no hint that help will come from elsewhere to save us from ourselves.

The Earth is the only world known, so far, to harbor life. There is nowhere else, at least in the near future, to which our species could migrate.

Visit, yes. Settle, not yet. Like it or not, for the moment, the Earth is where we make our stand. It has been said that astronomy is a humbling and character-building experience. There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world.

To me, it underscores our responsibility to deal more kindly with one another and to preserve and cherish the pale blue dot, the only home we’ve ever known.

More information about the Golden Record in Timothy Ferris’ article How The Voyager Golden Record Was Made.

The Illuminating Power of Eclipses

With the sun obscured, eclipses can be revelatory: Starting at least over 2,000 years ago, they have been fodder for significant discoveries.

A total solar eclipse showing the sun’s corona in Brazil in 1919. Credit Science & Society Picture Library, via Getty Images

Hipparchus, the Greek astronomer and mathematician who lived more than 2,000 years ago, used the solar eclipse to solve a celestial geometry problem.

He knew that at a spot in northwestern Turkey an eclipse had totally blocked the sun. But in Alexandria, about 1,000 kilometres away, only about four-fifths of the sun had been covered. From that tidbit, he calculated the distance between the Earth and moon to within roughly 20 percent of the correct figure.

Hipparchus was among the earliest scholars to take advantage of eclipses for science. In more recent centuries, scientists have used these celestial events as opportunities to study the solar system, especially the sun itself.

Usually, the sun is too bright for scientists to see anything in its immediate vicinity. Only during eclipses does its radiant halo, the corona, become visible.

In 1605, the German astronomer Johannes Kepler mused that the corona observed during an eclipse might be a consequence of an atmosphere around the moon scattering the passing sunlight. (Eventually, scientists figured out that the corona surrounded the sun, not the moon.)

Sun’s corona during total solar eclipse, 21 August 2017
National Park Service, US

The corona is the outer atmosphere of the sun. It is made of tenuous gases and is normally hiding in plain sight, overwhelmed by the bright light of the sun’s photosphere. When the moon blocks the sun’s face during a total solar eclipse, the corona is revealed as a pearly-white halo around the sun. To study the corona, scientists use special instruments called coronagraphs, which mimic eclipses by using solid disks to block the sun’s face. During a natural total eclipse, however, lower parts of the corona can be seen in a way that still cannot be completely replicated by current technology.

Eclipse observations are important for understanding why the sun’s atmosphere is 1 million degrees hotter than its surface, as well as the process by which the sun sends out a constant stream of solar material and radiation, which cause changes in the nature of space and may impact spacecraft, communications systems, and orbiting astronauts. But creates awesome auroras 🙂

NASA Image Credit: Luc Viatour

Observers also reported gigantic arcs rising out of the sun, solar prominences now known to stretch hundreds of thousands of miles into space.

The invention of the spectroscope in the mid 19th century brought new solar discoveries. A glass prism splits light into a rainbow of colours emitted by specific atoms and molecules — bar codes, in a way, that identify the elements making the light.

In 1868, a French scientist, Pierre Janssen, travelled to India to view an eclipse through a spectroscope. The sun’s prominences, he concluded, are largely made of hot hydrogen gas.

But a bright yellow line seen through the spectroscope, initially thought to be an identifier of sodium, did not match the wavelength of sodium.

That signified the discovery of helium, the universe’s second most common element. It would not be found on Earth for another 13 years.

The observatory of Norman Lockyer on the Kent Coast of England in 1890. Lockyer is one of the scientists credited with helping discover helium. Credit Science & Society Picture Library/Getty Images
Left, a photograph from 1878 of the sun’s surface, left, that was taken by the French astronomer Pierre Janssen, right. Credit Left: Science & Society Picture Library, via Getty Images; right: Oxford Science Archive/Print Collector, via Getty Images

During a total solar eclipse in 1869, two American scientists, Charles Augustus Young and William Harkness, independently observed an unexpected faint green line in the corona.

Scientists hypothesized it might be the emission of a new element, which was given the name coronium. It wasn’t until the 1930s that researchers realized coronium was not a new element, but rather iron with half of the atom’s 26 electrons stripped away.

That finding hinted at ultrahot temperatures on the sun — and at a new mystery.

The lines of colour seen on a spectrometer can also be used to measure temperature. The temperature of the surface of the sun is about 5,500 degrees Celsius (5,778 K).

Yet measurements of the corona, begun during a 1932 eclipse, put the temperature there much higher — millions of degrees. Ever since, solar scientists have been puzzling over precisely how the corona gets so hot.

Eclipses have taught scientists much about how our solar system works. But the events have also brought down some firmly held ideas.

Astronomers long ago discovered that Mercury, the innermost planet, wobbled in its orbit more than Newton’s laws of motion indicated it ought to. In the 19th century, many thought there must be another little planet inside the orbit of Mercury that was pulling it around. They called it Vulcan.

Various observers reported seeing a small dot cross in front of the sun, and many were convinced. “Vulcan exists, and its existence can no longer be denied or ignored,” The New York Times reported in September 1876.

During the darkness of a total solar eclipse two years later, two astronomers — one stationed in Wyoming, the other in Colorado — separately claimed to have spotted planets within the orbit of Mercury.

But they were wrong — they probably had seen well-known stars that become visible in the darkness of the eclipse. By the end of the century, most scientists doubted Vulcan was there, and in 1915, Einstein’s theory of general relativity provided a plausible explanation for Mercury’s wobble: a distortion in space-time caused by the sun.

Einstein’s ideas set the stage for the most famous eclipse experiment of all time, in 1919, during which Sir Arthur Eddington observed the bending of starlight around the sun. The findings verified the theory’s predictions.

Solar eclipses have been used not just to deduce what is going on in the solar system but also to study Earth.

In 1695, the astronomer Edmund Halley discovered that modern calculations did not quite predict eclipses reported in ancient times. As it turned out, that is because the Earth’s spin has been slowing.

Credit Science & Society Picture Library/Getty Images

Chinese historical records provided clues needed to figure out how much. In the 4th century BCE, a Chinese philosopher, Mozi, wrote that “the sun rose at night”, describing an epic battle that had occurred about 1,500 years earlier.

While paging through the text at the University of California, Los Angeles, a couple of decades ago, Kevin D. Pang, a former NASA scientist, realized this was not a poetic account of a fiery combat, but a description of a total eclipse.

The eclipse, which occurred close to sunset, indicated a passage into night, and the re-emergence of the sun was thus a sunrise at night.

The day and place of the battle were known. Computer simulations determined how much slowing of Earth’s rotation rate was needed to make the shadow of an eclipse that occurred that day pass over the battlefield.

If the Earth was spinning faster back then, the day was shorter — by 0.07 of a second.

Eclipses also provide a test of weather models. “We’re not normally in a position to turn something off and see what the response is in a nice cause-and-effect sort of way,” said Giles Harrison, a professor of atmospheric physics at the University of Reading in England.

When the sun disappears, temperatures drop and winds calm. Using weather station data from the 1900 eclipse that crossed North America, a meteorologist named H. H. Clayton noticed that the winds also appeared to change direction.

During a 2015 eclipse in England, Dr. Harrison and a colleague analysed weather station data and collected observations from several thousand citizen scientists. They found that the wind direction shifted 20 to 30 degrees because warm air had stopped rising from the ground.

“That largely confirms Clayton’s thinking, his ideas from over a hundred years ago,” Dr. Harrison said.

Original article in The New York Times.

The Solar Eclipse That Made Einstein Famous

It seems impossible, given how instantly recognizable Albert Einstein’s shock of white hair, bushy mustache and lined face remain six decades after his death, but there was a time when he was not famous. In fact, there was a time when the German-born prodigy was not a full-fledged physicist. Instead, he was patent examiner in Bern, Switzerland, who conducted scientific research in his off hours.

In 1905, when he was 26, Einstein began revolutionizing physics with his theory of special relativity, which helped redefine the relationship between space and time. One of the world’s most iconic mathematical equations — E=mc2 — grew out of special relativity.

Einstein Memorial in Washington, DC

That work secured Einstein a series of academic positions, but it didn’t make him famous. Neither did his theory of general relativity, which he published in 1915. Einstein argued that what we understand as gravity is, in fact, from the curvature of space and time — a hotly debated notion among physicists at the time.

Then came the solar eclipse of 1919 — more than six minutes of darkness along a path that stretched from South America to Africa and changed the course of Einstein’s life. Some people refer to the May 29, 1919, event “Einstein’s eclipse.”

Albert Einstein delivers a lecture to the American Association for the Advancement of Science in Pittsburgh on Dec. 28, 1934. (AP)

Nearly a century later, on Aug. 21, a solar eclipse will sweep across the United States in one of the most anticipated astronomical events in the country’s history. It will give scientists an opportunity to study the sun’s volatile corona, the wisps of plasma that billow and sometimes explode around the star.

In 1919, British astronomers, led by Sir Arthur Eddington, used the eclipse to prove that the light from stars was being deflected by the sun’s gravitational field at exactly the degree Einstein’s theory predicted.

Newspapers around the world celebrated the accomplishment. “Einstein Theory Triumphs,” the New York Times reported on November 10, 1919. “Men of Science More or Less Agog Over Results of Eclipse Observations.”

New York Times, November 10, 1919

What Einstein had done, effectively, was change the conversation about space, and how people understood and related to it. Just as importantly, the scientific breakthrough offered a reprieve from the devastation of World War I, which had claimed the lives of an estimated 17 million people.

“Europe was in mourning,” said Jimena Canales, author of The Physicist and the Philosopher: Einstein, Bergson, and the Debate That Changed Our Understanding of Time. “The public was thirsty for news that was not about what was going on around them.”

Einstein won the Nobel Prize in 1921. Afterward, he traveled the world, hobnobbing with royalty and Hollywood stars. Charlie Chaplin invited him to the premiere of his new movie, City Lights, in 1931, and reportedly said to him, “They’re cheering us both, you because nobody understands you, and me because everybody understands me.”

Einstein fled Germany in 1933 as the Nazis came to power and began ousting Jewish scientists from the country’s universities. In a speech to a packed audience at London’s Royal Albert Hall on October 3, 1933, Einstein warned of the dangers Hitler posed.

“If we want to resist the powers which threaten to suppress intellectual and individual freedom we must keep clearly before us what is at stake,” he said, “and what we owe to that freedom which our ancestors have won for us after hard struggles.”

He sailed to the United States four days later, eventually taking a position at the Institute for Advanced Study in Princeton, NJ, where his fame grew. He was a pacifist and an outspoken champion of civil rights, joining the NAACP and corresponding with W.E.B. Du Bois, a co-founder of the organization.

British scientist Stephen Hawking speaks in New York in 2016 while an image of Albert Einstein looms behind him on a video screen. (EPA/JASON SZENES)

“Einstein, in that time, was becoming more than a public scientist,” Canales said. “He became oracular, and he didn’t shy away” from it. “He created this new role [now inhabited] by people like Stephen Hawking and Carl Sagan.”

By the time he died in 1955 at the age of 76, Einstein’s name had become a synonym for genius. And it all began in 1919, after the moon briefly blocked the sun.

Original article in The Washington Post.

Griffith Observatory, Los Angeles
This statue of Albert Einstein demonstrates an extraordinary fact about what is in the sky. Einstein’s lifted index finger covers the amount of sky shown on the monumental wall across the room. The wall is known as The Big Picture, and it is the largest astronomical picture in the world. Almost of all its two million stars and galaxies can be seen only by telescope. It would take 1,357 Big Pictures to cover the whole sky. The Big Picture and Albert Einstein together reveal the true grandeur of the universe.
The Big Picture
Griffith Observatory, Los Angeles
Griffith Observatory, Los Angeles