In the centuries people have wondered about the possibility of other soils that circle in distant stars. Perhaps some of…
In the centuries people have wondered about the possibility of other soils that circle in distant stars. Perhaps some of these strange worlds would have wonderful forms of life or have unique and tell stories or futures. But it was only in 1995 that astronomers discovered the first planets that circled sunny stars beyond our solar system.
Over the last decade, the number of planets known to track remote stars increased from 100 to over 2,000, with another 2,000 likely planets awaiting confirmation. Most of these new discoveries depend on a single endeavor – NASA’s Kepler mission.
Kepler is a spacecraft that holds a 1
meter telescope that illuminates a 95 megapixel digital camera, the size of a cake. The instrument detected slight variations in the brightness of 150,000 distant stars and searched for a planet’s signaling character that blocks some of the starlight as it passes over the telescope’s field of view. It is so sensitive that it can detect a fly that surges around a single street lighting in Chicago from an orbit above the ground. It can see the stars shake and vibrate; it can see stars and spots; and in favorable situations it can see planets as small as the moon.
Kepler’s thousands of discoveries revolutionized our understanding of planets and planetary systems. Now, however, the spacecraft has completed its hydrazine fuel and officially retired pension. Fortunately for planet hunters, NASA launched TESS missions in April and takes over the exoplanet search.
The Kepler mission is discovered in the early 1980s by NASA scientist Bill Borucki, with the help of David Koch. At the time there were no known planets outside the solar system. Kepler was finally built in the 2000s and launched in March 2009. I joined the Kepler Science Team 2008 (like a big-eyed rookie) who ultimately led the group who studied the movements of the planet with Jack Lissauer.
Originally, the mission was planned to last for three and a half years with possible extensions as long as the fuel or camera or spacecraft lasted. As time passed, parts of the camera began to fail, but the mission has remained. However, in 2013, when two of its four stabilizing gyros (technical “reaction wheels” ceased), the original Kepler mission ended effectively.
Even then, with some ingenuity, NASA could use reflected light from the sun to help control spacecraft. The mission was rechristened as K2 and continued to find planets for another half a decade. Now, with the fuel meter near the site, the planetjakt’s operations and the spacecraft drop off are left in operation in the solar system. The final directory of planet candidates from the original mission was finalized at the end of last year and the last observations of K2 set aside.
Hugs what knowledge we can from these data will continue in the coming years, but what we have seen so far has surprised scientists worldwide.
We have seen a few planets that revolve around their host stars in a few hours and are so hot that the surface is rocking and jumping behind the planet like a comedy novel. Other systems have planets so close to each other that if you were standing on the surface of one, the other planet would show more than 10 full moon. A system is so packed with planets that eight of them lie closer to the star than the Earth is to the sun. Many have planets, and sometimes several planets that circulate within the hostile zone, where liquid water can exist on their surfaces.
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As with all quests, the Kepler package came with balances. It needed staring on a single part of the sky and blinked every 30 minutes for four straight years. In order to be able to study enough stars to make measurements, the stars must be quite remote – just like in the middle of a forest, there are more trees beyond you next to you. Removing stars is weak, and their planets are difficult to study. A challenge for astronomers who want to study the Kepler plan’s features is actually that Kepler itself is often the best instrument to use. High-quality data from ground-based telescopes require long observations on the largest telescopes – valuable resources that limit the number of planets that can be observed.
We now know that there are at least as many planets in the galaxy as there are stars, and many of these planets are quite different as we have here in the solar system. Learning the characteristics and personalities of the wide variety of planets requires astronomers to explore those who circle lighter and closer stars where more instruments and more telescopes can be worn.
NASA’s Transiting Exoplanet Survey Satellite Mission, led by MIT’s George Ricker, searches for planets using the same detection technology that Kepler used. TESS circulation, rather than being around the sun, has a close relation to the moon: TESS circles the earth twice for each lunar course. TESS “observation patterns, rather than staring at a part of the sky, will scan almost the entire sky with overlapping field of view (similar to petals on a flower).
Given what we learned from Kepler, astronomers TESS are expected to find thousands of more planetary systems. By mapping the entire sky we find systems that circle stars 10 times closer and 100 times lighter than those found by Kepler – opens new possibilities to measure planetary masses and densities, study the atmosphere, characterize the host stars and fully establish the nature of the systems where the planets live . This information will in turn tell us more about our own planetary history, how life may have begun, what fate we avoided and what other ways we could have followed.
The mission to find our place in the universe continues as Kepler ends his leg of the journey and TESS takes the relay.
Jason Steffen is a deputy professor of physics and astronomy at the University of Nevada, Las Vegas. This article was originally presented at The Conversation.