Astronomy

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

Astronomy — page 9 — surface areas to collect more light Hubble's Deepest Views Hubble's deepest views into space show galaxies more than 13 billion years old just as a larger bucket would collect more rainwater Astronomers found hints of EGS zs8 1 in photos from the Hubble Space Telescope an observatory orbiting Earth Hubble's main mirror is 7 9 feet 2 4 m across But For ten days in December 1995 the Hubble Space Telescope stared at a spot in the sky the same Size as a dime held 75 feet 23 m away Hubble's pictures revealed thousands of galaxies in that tiny region Astronomers have repeated this Hubble Deep Field process several times with the telescope after astronauts installed newer instruments in their 2012 image astronomers can count approximately 5 580 galaxies in that small region If such a tiny spot holds that many galaxies then that means the whole universe could have approximately 200 billion galaxies to look at the infrared light and confirm the galaxy's distance they used a huge telescope in Hawaii It collects light using a mirror 33 feet 10 m across A space telescope planned for a 2018 launch will be able to see even older galaxies The James Webb Space Telescope WST will detect the infrared light from the earliest galaxies It will also be bigger than Hubble at 21 feet 6 5m across Because it will fly far above our planet's atmosphere the JWST will have a clearer view into space than telescopes on Earth s surface Astronomers say it will be able to see the earliest stars and galaxies as they were just starting to light up This telescope will be able to see back to the universe s first 200 million years The Awesome Universe Astronomers are discovering many exciting things about our universe in addition to some of the first galaxies that formed They have found thousands of exoplanets They have learned giant black holes 12

Astronomy — page 10

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