Die Suche nach Exoplaneten hat ein Problem: Den Wissenschaftlern gehen die Teleskope aus. Nun hat die Europäische Weltraumorganisation dazu eine neue Mission auf den Weg gebracht – mit gleich 34 Teleskopen und Kameras an Bord.
While the Kepler Space Telescope has discovered more than 3,000 exoplanets with 709 confirmed that revolve around a star, new findings from diverse fields are being brought to bear of the central questions of the 21st century: How common is life in the universe? Where can it survive, Will it leave a fossil record? How complex is it? The list below moves several key features of the Universe off the chart of likely places to search for life.
Kepler has discovered exoplanets in alien star systems in an area that represents around 1/400th of the Milky Way. By extrapolating the numbers, the Kepler team has estimated that there are at least 50 billion exoplanets in our galaxy — 500 million of which sit inside the habitable „Goldilocks“ zones of their suns, the area that is neither too hot nor too cold to support life.
Astronomers estimate that there are 100 billion galaxies in the Universe. If you want to extrapolate those numbers, that means there are around 50,000,000,000,000,000,000 (50 quintillion) potentially habitable planets in the universe.
Gibt es Leben in unserer kosmischen Nachbarschaft? Astronomen haben bei einem nahen Stern drei Gesteinsplaneten entdeckt, die in der bewohnbaren Zone liegen.
Astronomers have discovered a new super-Earth in the habitable zone, where liquid water and a stable atmosphere could reside, around the nearby star HD 40307. HD 40307 is an orange (K-type) main sequence star located approximately 42 light-years away in the constellation of Pictor (the Easel). It is calculated to be slightly less massive than the Sun with six known planets orbiting it. In 2008, three extrasolar planets were discovered in orbit around the star –found to be hot super-Earths because they orbit too close to the star to support life.
In 2012, three more planets were discovered orbiting HD 40307. One of them, HD 40307 g is a Super-Earth with orbital period about 200 days, and might be capable of supporting liquid water. The three planets were found by an international team, including Carnegie co-author Paul Butler, led by Mikko Tuomi of the University of Hertfordshire and Guillem Anglada-Escudé of the University of Göttingen who used newly developed software that is able to process the signals more thoroughly, re-analyzing spectra detected by the radial velocity method, using the HARPS spectrograph system through the European Southern Observatory.
The Kepler Space Mission’s search for habitable planets is in a tiny window representing 1/400th of the Milky Way. „We used to think that the Earth might be unique in our galaxy,“ said Daniel Kubas, of the Paris Institute of Astrophysics. „But now it seems that there are literally billions of planets with masses similar to Earth orbiting stars in the Milky Way.“
According to an analysis of Kepler data this past January, each of the 100 billion or so stars in our galaxy hosts at least 1.6 planets, bringing the number of likely exo worlds to more than 160 billion. Recent research conclude that large numbers of these exoplanets are likely to be small, rocky Earth-like low-mass planets, which appear to be much more abundant than large ones.
„This statistical study tells us that planets around stars are the rule, rather than the exception,“ said study lead author Arnaud Cassan of the Paris Institute of Astrophysics. „From now on, we should see our galaxy populated not only with billions of bright stars, but imagine them surrounded by as many hidden extrasolar worlds.“
To date, astronomers have discovered more than 700 planets beyond our own solar system, with 2,300 additional candidates found by NASA’s Kepler space telescope awaiting confirmation.
Alien Habitable Planets May Exist Billions of Years Older Than Earth –Harvard Center for Astrophysics
Building a terrestrial planet requires raw materials that weren’t available in the early history of the universe. The Big Bang filled space with hydrogen and helium. Chemical elements like silicon and oxygen – key components of rocks – had to be cooked up over time by stars. But how long did that take? How many of such heavy elements do you need to form planets?
Previous studies have shown that Jupiter-sized gas giants tend to form around stars containing more heavy elements than the Sun. However, new research by a team of astronomers found that planets smaller than Neptune are located around a wide variety of stars, including those with fewer heavy elements than the Sun. As a result, rocky worlds like Earth could have formed earlier than expected in the universe’s history.
„This work suggests that terrestrial worlds could form at almost any time in our galaxy’s history,“ said Smithsonian astronomer David Latham (Harvard-Smithsonian Center for Astrophysics). „You don’t need many earlier generations of stars.“* Latham played a lead role in the study, which was led by Lars A. Buchhave from the University of Copenhagen and will be published in the journal Nature. The work is being presented today in a press conference at the 220th meeting of the American Astronomical Society.
A few hundred thousand billion free-floating life-bearing Earth-sized planets may exist in the space between stars in the Milky Way. So argues an international team of scientists led by Chandra Wickramasinghe, Director of the Buckingham Center for Astrobiology at the University of Buckingham, UK. The scientists have proposed that these life-bearing planets originated in the early Universe within a few million years of the Big Bang, and that they make up most of the so-called “missing mass” of galaxies. The team calculated that such a planetary body would cross the inner solar system every 25 million years on the average and during each transit, zodiacal dust, including a component of the solar system’s living cells, becomes implanted at its surface. The free-floating planets would then have the added property of mixing the products of local biological evolution on a galaxy-wide scale.
Since 1995, when the first extrasolar planet was reported, interest in searching for planets has reached a feverish pitch. The 750 or so detections of exoplanets are all of planets orbiting stars, and very few, if any, have been deemed potential candidates for life. The possibility of a much larger number of planets was first suggested in earlier studies where the effects of gravitational lensing of distant quasars by intervening planet-sized bodies were measured.
Certainly you remember the story of Goldilocks and the tree bears told to you as a child by a knowing adult? What does a fairy tale have to do with Space exploration? As the numbers mount, it seems to be just a matter of time before Kepler finds what astronomers are really looking for: an Earth-like planet orbiting its star in the „Goldilocks zone“—that is, at just the right distance for liquid water and life.
„I believe Kepler will find a ‚Goldilocks planet‘ within the next two years,“ says Shawn Domagal-Goldman, a researcher at NASA HQ who specializes in exoplanet biology. „We’ll be able to point at a specific star in the night sky and say ‚There it is—a planet that could support life!'“
Kepler has already located a few Earth-sized planets, but they are too close for comfort to their parent stars. These recent finds have heightened the sense that a big discovery is just around the corner.
Ein europäisches Forscherteam hat neu abgeschätzt, wie viele lebensfreundliche Planeten es in unserer kosmischen Nachbarschaft geben könnte. Die Zahl fällt extrem hoch aus – auch wenn viele der Himmelskörper wohl regelmäßig von Strahlungsblitzen geröstet werden.
Ein internationales Forscherteam will einen besonders lebensfreundlichen Planeten in einem nahen Sternsystem aufgespürt haben. Auf der Suche nach einer zweiten Erde halten sie den Himmelskörper GJ 667Cc für den bisher spannendsten Kandidaten.
In fünf Milliarden Jahren wird es auf der Erde ziemlich heiß: Die Sonne wird sich aufblähen und unseren Planeten verschlingen. Astronomen haben jetzt zwei Planeten gefunden, die durch solch eine Gluthölle gegangen sind – und irgendwie überlebt haben.
„Aliens could have been pointing their antennas at Earth for 4.6 billion years, without picking up a signal. Maybe the inhabitants [of a Twin Earth] are at the level of the classical Romans … or maybe trilobites. We need to check out hundreds of thousands of Earthlike worlds.“
NASA announced that Kepler has uncovered 1,094 more potential planets, twice the number it previously had been tracking, including more than 500 planets found to orbit stars beyond our solar system. IThe newly discovered Kepler 22-B is the smallest and the best positioned to have liquid water on its surface – among the ingredients necessary for life on Earth. It is 2.4 times the size of the Earth, putting it in a class known as “super-Earths”.
Ein Zwilling unseres Planeten, bewohnbar wie die Erde: Das Nasa-Weltraumteleskop Kepler hat nun den Beweis erbracht, dass es ihn gibt. Der Himmelskörper Kepler 22b umkreist in 600 Lichtjahren Entfernung einen sonnenähnlichen Stern – und bietet Bedingungen, unter denen Leben möglich wäre.
In two new videos from NASA’s Deep Impact spacecraft, bright flashes of light known as sun glints act as beacons signaling large bodies of water on Earth. These observations give scientists a way to pick out planets beyond our solar system (extrasolar planets) that are likely to have expanses of liquid, and so stand a better chance of having life. ‚
These sun glints are like sunshine glancing off the hood of a car. We can see them reflecting off a smooth surface when we are positioned in just the right way with respect to the sun and the smooth surface. On a planetary scale, only liquids and ice can form a surface smooth enough to produce the effect—land masses are too rough—and the surface must be very large. To stand out against a background of other radiation from a planet, the reflected light must be very bright. We won’t necessarily see glints from every distant planet that has liquids or ice.
Wie viele Planeten gibt es allein in unserer Galaxis? Mithilfe des Nasa-Teleskops „Kepler“ wollen US-Forscher diese Frage beantworten. Die Zählung im All liefert beeindruckende Daten: 50 Milliarden Planeten sollen es sein, Leben könnte auf 500 Millionen existieren.
NASA’s Kepler mission confirmed the discovery of its first rocky planet, named Kepler-10b. Measuring 1.4 times the size of Earth, it is the smallest planet ever discovered outside our solar system. The discovery of this planet, called an exoplanet, is based on more than eight months of data collected by the spacecraft from May 2009 to early January 2010.
„All of Kepler’s best capabilities have converged to yield the first solid evidence of a rocky planet orbiting a star other than our sun,“ said Natalie Batalha, Kepler’s deputy science team lead at NASA’s Ames Research Center in Moffett Field, Calif. „The Kepler team made a commitment in 2010 about finding the telltale signatures of small planets in the data, and it’s beginning to pay off.“
US-Astronomen haben in den Weiten des Alls zwei Planeten entdeckt. Einer davon weist Ähnlichkeiten zu unserer Erde auf – und ist möglicherweise für die Entstehung von Leben geeignet.
Astronomer Dimitar Sasselov and his colleagues search for Earth-like planets that may, someday, help us answer centuries-old questions about the origin and existence of biological life elsewhere (and on Earth). How many such planets have they found already? Several hundreds.