It may not be possible to travel back in time, but seeing stars and galaxies as they looked millions or even billions of years ago is no problem thanks to telescopes, the closest thing we have to time machines.
(CNN) — It may not be possible to travel back in time, but seeing stars and galaxies as they looked millions or even billions of years ago is no problem thanks to telescopes, the closest thing we have to time machines. Now, astronomers are holding their breath to see what they’ll observe and discover with a new generation of huge telescopes set to be built around the world. Peering ever deeper into space and further back in time, the powerful devices will be able to show what the universe was like when it was just a few hundred million years old and emerging from a period of total darkness after the Big Bang. “[We’ll be] looking at the first generation of stars forming in the universe, which is kind of a cool idea: The time when the lights went on in the universe. There was no light before that time,” said Daniel Fabricant, associate director of the Harvard-Smithsonian Center for Astrophysics. His institution is one of several research organizations and universities developing the Giant Magellan Telescope, to be built in Las Campanas, Chile, by 2018. ‘Eye on the sky’ Bigger is better in the world of reflecting telescopes, which rely on primary mirrors to collect light. The bigger the primary mirror, the more light it can gather and the fainter the objects astronomers can see. The world’s largest optical and infrared telescopes have primary mirrors that measure about 10 meters (32 feet) across. But the Giant Magellan Telescope will more than double that diameter, with a monster primary mirror spanning almost 25 meters (80 feet). If the Magellan is the first new-generation star gazer to be built, it may not remain the record holder for long. Another consortium of organizations and universities is preparing to construct the aptly named Thirty Meter Telescope on the Mauna Kea summit in Hawaii, also scheduled for completion in 2018.
Big Bang 101• The Big Bang Model is a broadly accepted theory for the origin and evolution of the universe.• It suggests that about 13.7 billion years ago, the portion of the universe we can see today was only a few millimeters across.• It has since expanded from this hot, dense state into the vast and much cooler cosmos we live in.• The Big Bang did not happen at a single point in space as an “explosion.” • It is better thought of as the simultaneous appearance of space everywhere in the universe.• The “Dark Ages,” a period of time when there was no light, followed the Big Bang. • The first objects illuminated the universe a few hundred million years later.Source: NASA.gov
Trumping them all may be the European Extremely Large Telescope, dubbed “the world’s biggest eye on the sky,” which is to have a primary mirror 42 meters (137 feet) in diameter and is also scheduled to start operation in 2018. No site has been chosen, though Argentina, Chile, Morocco and Spain are being considered. Astronomers hope these giants will fill in gaps in knowledge about key moments in the early days of the universe. See some of the amazing photos taken by the Hubble Space Telescope “Right now, we can see to almost 13 billion years [back], but our best models tell us the age of the universe is almost 14 billion years, so it’s this whole epoch when galaxies are actually first starting to form that we can’t really see very well,” said Elizabeth Barton, an assistant professor of astronomy at the University of California, Irvine, and a member of the Science Advisory Committee for the Thirty Meter Telescope. “So the Thirty Meter Telescope will let us do things like find some of the first galaxies to form and characterize them to figure out what the conditions were actually like and how big these things were when they were forming.” Blog: Will the Big Crunch follow the Big Bang Seeing the past Looking so far back in time may sound like science fiction, but it’s possible because light travels at a finite speed and takes a certain amount of time to get from one place to another, said Marla Geha, an assistant professor of astronomy at Yale University. In our own cosmic neighborhood, it takes the light from the sun eight minutes to reach Earth, so when you look at a beautiful sunrise, you see the star as it appeared eight minutes ago. If the sun were to suddenly go dark, you wouldn’t know it for those several minutes. The same concept of seeing objects as they appeared in the past holds true on a much bigger scale.
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“The light from the nearest star [outside the solar system] takes a couple of years to get to us. The light from the farthest star in the Milky Way takes a couple of million years to get to us,” Geha said. “Since the universe is about 14 billion years old, and as we’re looking at things that are farther away, we’re looking at light that’s taken half or more than half of the age of the universe to get to us.” Some of that light is from the first stars to ever form — fascinating to astronomers because they were probably much larger and brighter than those we find in the present-day universe, Fabricant said. Closer to home, astronomers hope to see planets orbiting other stars — perhaps young “Earths” in the process of formation — and observe other solar systems, he added. Sharper than Hubble The pictures will likely be spectacular. Despite being ground-based, all of the next-generation telescopes promise images several times sharper than those produced by the orbiting Hubble Space Telescope thanks to adaptive optics, technology that corrects for the “wiggling” of the Earth’s atmosphere. Twinkling stars may be romantic to look at, but they’re a big headache for astronomers trying to get a sharp picture. One way to combat the distortion is to shoot laser beams into the sky to create fake stars and then measure how their appearance is changed by the atmosphere and take the appropriate counter-measures — all at hundreds of times a second. “You know what a perfect image looks like, you know what you observe, and then you know what you need to do to correct the image,” Fabricant said. “The idea is … to have the mirror wiggle exactly opposite to take out the twinkling,” Geha added. Until the ground-based giants are built, Hubble’s successor, the James Webb Space Telescope, will be helping to answer key questions about the universe. Webb is scheduled to be launched in 2014, about the time Hubble’s mission will end. Operating much farther from Earth and equipped with a primary mirror more than twice the diameter of Hubble’s, Webb is designed to look deeper into space to see the earliest stars and galaxies, according to NASA. Researchers on the competing projects say there’s a certain rivalry about making the big discoveries but emphasize that the most important thing is that somebody makes them. “It’s a competition where you want the other guy to succeed as well,” Fabricant said.
