Astronomy

Astronomy — page 5 — The gravity of distant objects can distort and magnify light creating a gravitational lens The result can be a circular ring of light around a celestial object right billions of years Our universe is now approximately 13 8 billion years old These very distant galaxies formed in the universe's first 1 billion years Astronomers are looking for the first galaxies that lit up our cosmos Every year they break their distance records New technology lets them collect older light Look to the Light Light is astronomy's crucial messenger Many types of light exist and each kind has a certain energy depending on its wavelength To visualize what wavelength is imagine two people holding a string loosely between them One person starts moving his arm up and down to create a wave The distance from one peak of the string's wave to the next peak is the wave's wavelength Light s Wavelength dictates what type of light it is The kind of light human eyes can see ranges from red light to violet The colors vary based on wavelength But beyond the narrow band of wavelengths we can see light also comes in forms we cannot see All types of light fall along what is called the electromagnetic

Astronomy — page 6 — 10 12 10 1 nanometer 104 1 micron 10 1 millimeter 10 1 meter 10 1 kilometer X ray Microwave Gamma rays traviolet WWWWWWWWWWWWWWWWVVSS Visible light Visible light only occupies a narrow sliver of the electromagnetic spectrum How do the wavelengths of different types of light compare Red has a longer wavelength than violet Infrared light has a longer wavelength than red light Microwaves and radio waves have even longer wavelengths Longer wavelength light carries less energy than shorter wavelength light Several types of light have shorter wavelengths than we can see with the naked eye Ultraviolet light X rays and gamma rays are all included in this group These types of light carry a great deal of energy They are often associated with high energy events in space such as massive explosions Astronomers have developed tools to observe many different wavelengths of light in space Spying Light from Galaxies The light from galaxies reveals their distances To study a galaxy astronomers examine its light in many wavelengths If that galaxy appears to be moving toward Earth astronomers see its light get a bit bluer in color Its light is shifted to smaller wavelengths If the galaxy appears to be moving away from us the light is a bit redder It has longer wavelengths These color changes happen for the same reason you hear a slightly higher pitched sound from a train or ambulance coming toward you than you do when it is moving away This phenomenon is called the Doppler

Astronomy — page 7 — Shifting Light Top To an observer on Earth a galaxy that appears to be stationary with relation to Earth will have its light at the expected region of the electromagnetic spectrum Middle To an observer on Earth a galaxy that appears to be moving away from Earth will have its light pushed toward the red end of the spectrum Bottom To an observer on Earth a galaxy that appears to be moving toward Earth will have its light pushed toward the blue end of the spectrum When astronomers look at a galaxy they look for these kinds of patterns in the light They can determine how fast the galaxy appears to be speeding toward or away from us In reality the space between galaxies is being stretched rather than the galaxies themselves moving through space When astronomers look at all the wavelengths of light the stars in a galaxy give off they see some colors that are special Specific elements give off certain colors of light For instance atoms of 10

Astronomy — page 8 — hydrogen the most common element in the universe emit violet aqua and red light Scientists can study A Distant Record Holders these colors to determine what elements make up Astronomers have found thousands of faraway celestial objects Astronomers have discovered our universe is expanding over time As it grows bigger galaxies planets orbiting other stars Most are Within a few thousand light years of Earth However two known exoplanets are approximately 2 800 light years from Earth Most stars astronomers can see lie in our Milky Way galaxy The most distant star they have found in our galaxy lies approximately 890 000 light years from us It is in the galaxy s dim outskirts move farther away from one another The expansion also stretches the light from those galaxies So even though the hydrogen in a far away galaxy gives off the violet aqua and red colors the expansion of space has A few stars explode at the end of their lives resulting in a supernova stretched that light Each color is shifted toward the This explosion disperses material into red end of the spectrum Light also tells astronomers space These blasts are very bright and astronomers can see them from how far away a galaxy is far away The most distant supernova they have found so far exploded In May 2015 astronomers found light that left a more than 10 billion years ago galaxy when it was just 570 million years old That light has been traveling for 13 1 billion years This galaxy is moving away from us very fast and it now lies very far away This galaxy named EGS zs8 1 became the oldest and most distant galaxy astronomers had found yet Find the First Ones The continuing search for the oldest and most distant galaxies is a direct result of improvements in telescope technology Larger telescopes can see fainter objects This is because they have larger 11

7

PAGE 7 OF 109

The only kids' eBook subscription service that offers thousands of high-quality books from well known publishers like HarperCollins, National Geographic and others.

JavaScript Required

Whoops! We're sorry but Epic doesn't work properly without JavaScript enabled. Check your web browser's settings to make sure it's enabled.