The discovery of seven Earth-sized planets orbiting the star TRAPPIST-1 generated a lot of excitement last week. Earth-sized planets have been found before, among the thousands of exoplanets discovered so far by astronomers, but this is the first time that so many have been detected in one planetary system. As of now, astronomers are limited in how much they can learn about these new worlds, but the James Webb Space Telescope, the upcoming successor to Hubble due to launch in 2018, will be able to gather more data and analyze whatever atmospheres these planets have, perhaps bringing us closer to finding another habitable world.
The search for exoplanets – planets orbiting other stars – has been one of the most exciting developments in astronomy and space science in recent years. The first couple exoplanets were found in 1992, and now over 3,400 have been confirmed, with over 5,000 additional candidates. Some of these are smaller rocky worlds similar in size to Earth, bringing scientists close to finding “Earth 2.0” – another planet with water and, perhaps, life. Yesterday, NASA announced another key discovery, bringing us even closer to finding another living world – a star with not just one or two Earth-sized planets orbiting it, but seven. Three of those planets are in the star’s habitable zone, where, depending upon other surface conditions, lakes or oceans of liquid water could exist.
NASA’s Juno spacecraft has been orbiting the gas giant planet Jupiter since July 4, 2016, and has already greatly increased scientists’ understanding of this fascinating world, the “King of Planets.” For the past while now, Juno has been in an elongated 56-day orbit, which brings the spacecraft close in over the cloud tops before swinging out farther away from the planet again. The plan had been for Juno to then switch to a closer, 14-day orbit, but due to growing concerns over another engine burn possibly resulting in a less-than-desirable new orbit, that plan has now been scrapped. Juno will now remain in its current orbit for the remainder of the mission.
For decades now, Europa has beckoned – this moon of Jupiter which is frozen on the outside but hides a global ocean on the inside – has so far only been visited by spacecraft during brief flybys. Scientists and the public alike have been wanting to return to this fascinating little world since it offers the possibility of maybe, just maybe, being home to some kind of life. Plans have been inching forward for a new mission to conduct multiple, closer flybys of Europa, to learn more about the ocean just below the ice, but what about actually landing? A lander would be a more difficult prospect since Europa doesn’t have an atmosphere, but is certainly doable. Now, NASA has received a formal science report on how best to conduct such a mission. This is a significant step toward finally being able have the view of looking up at Jupiter hanging in the inky black Europan sky – a dream of many for a long time.
The subject of water on Mars is one of the most highly debated in planetary science; various missions have provided ample evidence that the planet used to be a lot wetter than it is now, with rivers, lakes and maybe even oceans. Most scientists now generally agree on this, but as to how much water there was, how long it lasted and how warm the environment was, is another question. There have been apparent conflicting lines of evidence, and now findings from the Curiosity rover have only added to the mystery. Curiosity has revealed a paradox of sorts – it has found abundant evidence for ancient lakes in now-dry Gale crater, but at the same time has not found evidence for a previous thicker atmosphere with more carbon dioxide, which normally would be needed for water to remain liquid on the surface. These two lines of evidence seem to contradict each other, so how to resolve this puzzle?
Asteroids are some of the most ancient objects in the Solar System, relics left over from the time when the planets first started forming and evolving. For this reason, scientists are very interested in them, since they can provide clues as to how this process occurred. Most asteroids orbit the Sun in a broad belt between Mars and Jupiter, but they can be found elsewhere in the Solar System as well. NASA’s OSIRIS-REx spacecraft is now en route to one of these asteroids, called Bennu, which it will study and then bring a sample back to Earth. While on the way there, however, OSIRIS-REx will also be searching for other asteroids, called Trojans. These have regular orbits which place them either just before or just behind a planet, including Earth. The spacecraft will be on the lookout for some of these Trojans near Earth this month as it travels toward Bennu.
Long after its incredible encounter with Pluto and its moons in 2015, the New Horizons spacecraft is continuing its journey deeper into the Kuiper Belt in the outer reaches of the Solar System. Mission scientists and engineers are now preparing for its next close flyby, of a smaller body called 2014 MU69, on Jan. 1, 2019. Along the way, New Horizons makes occasional slight course corrections to keep it on track, and now the spacecraft has just successfully completed its latest one.
As the Cassini spacecraft continues its journey through the Ring-Grazing Orbits, it has been sending back some incredible new images of Saturn and its rings, many in detail never seen before. The rings are composed of countless individual streams of particles, all held in place by Saturn’s gravity. Click to view full-size versions of the raw images. All Cassini raw images are available here.
The Juno spacecraft has sent back a beautiful new view of Jupiter’s “Little Red Spot,” a smaller and paler version of the Great Red Spot, which is an anticyclone in the atmosphere (a large-scale circulation of winds around a central region of high atmospheric pressure). Other complex cloud patterns can also be seen. The image was first taken on Dec. 11, 2016. The amazing full image is below: