A team from NASA working with light, have undertaken a project for IYL2015 called “Light: Beyond the Bulb”, mainly an online collection of beautiful images, with the goal to showcase the enormous spectrum of things that light does. It would be impossible to represent everything that light can do, but the image collection provides some of the most stunning examples they could find: from brain imaging to bioluminescence, from lasers to light pollution, and from auroras to astronomy.
These are some of our favourite images. You will find the entire collection, and the credits for all the images, at http://lightexhibit.org
Astrocytes are the star-shaped cells found in spinal cord and the brain. In fact, they are the most abundant cells in the human brain. In this image of astrocytes, the nucleus of each cell has been stained blue while the cytoplasm (the fluid that fills the cell) has been colored green. To achieve this, the process of immunofluorescence was used. Immunofluorescence is a staining technique that uses antibodies to attach fluorescent dyes to specific tissues and molecules in the cell.
While most people are familiar with “grey matter” associated with the brain, many people may not know about white matter. This is a network, made up of nerve fibers, that connects different parts of the brain and spinal cord to one another. This image was made using diffusion spectrum imaging (DSI), which is a variant of magnetic resonance imaging. In DSI, radio waves from water molecules energized by a magnetic field map the water contained in neuron fibers, which, in turn, reveals their criss-crossing patterns. Scientists are using this technique and others like it to make a comprehensive map of neural connections—a “wiring diagram,” so to speak—in the brain.
Most objects do not emit light. Rather, they reflect it from a source like a light bulb or sunlight. This common process allows us to see these things that are all around us. In fact, one of the fundamental laws of the physics of light involves reflection. Reflection consists of two rays: an incoming or ‘incident’ ray and an outgoing or ‘reflected’ ray. All reflected light obeys the rule that says the incident ray strikes a surface at the same angle that the reflected ray bounces away from it. In the case of a smooth surface like a mirror or, in the case of the photograph, the calm top of a lake, a clear identical image is produced.
At sunrise and sunset, light from the Sun must take a much longer path through the Earth’s atmosphere than it does during the middle part of the day. This means more of the blue and indigo light of sunlight is scattered away because these shorter wavelengths of visible light are more affected by air molecules in the atmosphere. This often allows more of the red and orange light to reach the Earth’s surface. Other factors — including dust, pollution, haze, and cloud formations – may also affect the colors of a sunset, creating a more complicated palette of light as the Sun dips below the horizon.
Some of the most famous light shows in the world are called auroras or, more commonly in the Northern Hemisphere, the “Northern Lights.” What causes these spectacular displays? Streams of particles with electric charge are continually leaving the Sun and traveling through the Solar System. As these particles approach the Earth, some of them are channeled by the planet’s magnetic field toward the North and South Poles. When these particles collide with atoms in the Earth’s atmosphere, the atoms in the atmosphere are excited give off light of a particular color tied to that type of atom.
Streams of particles with electric charge are continually leaving the Sun and traveling through the Solar System. As these particles approach the Earth, some of them are channeled by the planet’s magnetic field toward the North and South poles where they collide with atoms in the Earth’s atmosphere. This produces the famous light shows we call auroras, or, more commonly in the Northern Hemisphere, the “Northern Lights.” The array of colors in auroras is due to the fact that different atoms emit different colors when they get pumped up with energy from collisions. Oxygen, for example, will create a greenish-yellow or a red light. Nitrogen will generally give off blue.
Many people have been lucky enough to see a “shooting star.” However, this name is misleading because these brief streaks of light seen in the night sky actually have nothing to do with stars. Rather, these are tiny bits of debris usually left behind by a comet traveling through the Solar System. If the Earth passes through this debris trail, hundreds or even thousands of these cosmic bits enter the Earth’s atmosphere. When these meteors enter the atmosphere, they are moving at speeds ranging from 11 km/sec (25,000 mph) to 72 km/sec (160,000 mph), and collide with numerous air molecules. These collisions create a vapor of atoms that is a mixture of energized atoms from the meteors and the atmosphere. As the electrons in these atoms fall back to their normal orbits, light is emitted, creating the bright trail light visible from the ground below.
As a so-called spiral galaxy, our Milky Way galaxy contains majestic arms of stars, dust, and gas that emanate from a central bulge area. Our Solar System resides in one of the outer arms of the Milky Way. When we look toward the center of the Milky Way, as we do in this photograph, we see a swath of starlight across the sky. This, however, is only a small percentage of the total stars there, as the dust and gas block much of our view in visible light.
Despite being 150 million kilometers from the Earth, the Sun delivers approximately 5 trillion giga-joules of energy to the Earth’s surface every year. This is a tremendous amount of energy. In fact, if we could harness just one day’s worth of the Sun’s energy that reaches us, we could power the entire planet’s energy needs for seven decades. Of course, it’s not technologically feasible to try to capture all of the Sun’s output, but the Sun holds enormous potential for providing energy to the Earth’s inhabitants. As solar panels gain in efficiency and other advances are made, look to the Sun and its light to play an important role in powering the planet and its needs.
This galaxy is so bright in the southern night sky that navigators for centuries have used it to help guide them across the ocean. Modern telescopes reveal there is much more to this object than just being a bright prick of light seen from sea. This image combines three different types of light to give us this spectacular view of this neighboring galaxy to the Milky Way. In this view of the so-called Small Magellanic Cloud (named after Ferdinand Magellan), X-ray light is purple, infrared light is red, and optical light is red, green, and blue. Together, these different slices of light give us a more complete picture of a stellar nursery where stars like our Sun are being born.
New Chandra observations have been used to make the first detection of X-ray emission from young stars with masses similar to our Sun outside our Milky Way galaxy. The Chandra observations of these low-mass stars were made of the region known as the “Wing” of the Small Magellanic Cloud (SMC), one of the Milky Way’s closest galactic neighbors. In this composite image of the Wing the Chandra data is shown in purple, optical data from the Hubble Space Telescope is shown in red, green and blue and infrared data from the Spitzer Space Telescope is shown in red. Astronomers call all elements heavier than hydrogen and helium – that is, with more than two protons in the atom’s nucleus – “metals”. The Wing is a region known to have fewer metals compared to most areas within the Milky Way. The Chandra results imply that the young, metal-poor stars in NGC 602a produce X-rays in a manner similar to stars with much higher metal content found in the Orion cluster in our galaxy.
The Orion Nebula, a region just to the south of the belt in the constellation bearing his name, is an active and boisterous stellar nursery. This image of the Orion Nebula is in infrared light, which, in contrast to light at visible wavelengths, passes through the dust that pervades the nebula, and reveals the very young stars buried within.
This wide-field view of the Orion Nebula (Messier 42), lying about 1350 light-years from Earth, was taken with the VISTA infrared survey telescope at ESO’s Paranal Observatory in Chile. The new telescope’s huge field of view allows the whole nebula and its surroundings to be imaged in a single picture and its infrared vision also means that it can peer deep into the normally hidden dusty regions and reveal the curious antics of the very active young stars buried there. This image was created from images taken through Z, J and Ks filters in the near-infrared part of the spectrum. The exposure times were ten minutes per filter. The image covers a region of sky about one degree by 1.5 degrees.
Another website worth checking out is http://www.fromearthtotheuniverse.org, for the open exhibition project From Earth to the Universe for the International Year of Astronomy 2009.