Astronomers today announced one of the most exciting exoplanet discoveries yet: an Earth-mass rocky world orbiting the nearest star to the Sun, Proxima Centauri. There had been hints before of such a world, but nothing was confirmed, until now. The planet, called Proxima b, is not only just slightly more massive than Earth, it orbits within the star’s “habitable zone.” The estimated temperatures of the planet could allow liquid water to exist on its surface. Not only is this planet potentially habitable, depending on other factors, it is also now the closest known exoplanet.
Over the past couple decades, astronomers have been discovering a seemingly endless variety of exoplanets orbiting other stars. Some are rather similar to planets in our own Solar System, while others are more like ones depicted in science fiction, ranging from rocky worlds about the size of Earth and larger, to massive, searing hot planets larger than Jupiter orbiting very close to their stars. Tatooine is another well-known example – the desert planet orbiting two suns in the Star Wars films. Now astronomers have found a similar world, using direct imaging, but which orbits within a system of three stars.
For several years now the Kepler Space Telescope, as well as other telescopes, has been discovering an increasing number of exoplanets, with over 2,000 such confirmed worlds found so far (and nearly 5,000 candidates). Today, NASA announced that the Kepler mission has added 1,284 newly confirmed exoplanets to that list, vastly increasing the number of known planets orbiting other stars. This is the largest number of new planets ever announced at one time. The new results were announced during a NASA teleconference briefing.
Exoplanets are now being discovered by the thousands, but most are so far away that determining anything specific about their composition or atmosphere is currently very difficult. But technology keeps advancing, and scientists are now starting to be able to learn more about them, at least ones which are a bit closer to our own Solar System. One of the most common types of exoplanets are the “super-Earths,” which are larger and more massive than Earth but smaller than Uranus or Neptune. Now, astronomers have been able to analyze the atmosphere of one of these worlds for the first time.
As has been reported previously, there is something weird going on around a star which is a little over 1,400 light-years away. Astronomers are still baffled as to just what that is, and theories have ranged from a huge mass of comets to alien megastructures. Indeed, comets had become the leading explanation offered for the star’s odd behaviour, although that was really just the best of a bunch of ideas which all had flaws in them. Now, new research shows that the comet explanation is even less likely to be the answer, although the actual explanation is still as elusive as ever. Needless to say, this has resulted in a lot of discussion and debate in the past few months.
Planetary debris disks, or protoplanetary disks, are some of the most interesting phenomena in astronomy – these giant clouds of dust and gas surrounding young stars are the birthplaces of new planets. Now, astronomers studying one of these disks have found structures never seen before, giant “ripples” which are arch-like or wave-like in appearance.
We still don’t know if there is life elsewhere in the universe, but scientists are working on techniques to better understand how it may have originated anyway, in the event that such alien biology is indeed discovered, even if just simple microbes. Focusing on exoplanets, the research suggests that if multiple inhabited worlds were found, then researchers could look for patterns similar to those found in epidemics on Earth, which might provide evidence for panspermia, the theory that life could spread through our galaxy from one habitable planet to another.
The Gemini Planet Imager, a new telescopic instrument designed to find, image, and study faint, young planets orbiting bright stars, has discovered its first exoplanet: a young Jupiter-like planet called 51 Eridani b which orbits the star 51 Eridani, about 100 light-years away. Thought to be similar to a younger version of Jupiter, it should help astronomers learn more about how planetary systems form.
One of the primary goals in the search for exoplanets is to, hopefully, find an Earth analog or “Earth twin,” an alien world similar to our own. That search is still ongoing, but getting closer – yesterday NASA announced a new exoplanetary discovery that could be described as “Earth’s bigger and older cousin” – Kepler-452b.