This week marks another important milestone in the Cassini mission at Saturn – as of today, the spacecraft is conducting the last Ring-Grazing Orbit of its mission as it prepares for the Grand Finale, which will culminate in the death of the probe on Sept. 15. On April 21, Cassini will do its very last close flyby of Saturn’s largest moon Titan. Speaking of Titan, Cassini has also apparently solved a perplexing mystery; the unusual “magic island” formations seen in one of the moon’s methane/ethane seas are now thought to be caused by nitrogen bubbles fizzing periodically on the sea’s surface.
There is an interesting new paper out about the seven near-Earth-sized exoplanets orbiting the star TRAPPIST-1. According to the study, four of the planets may be true water worlds, although just what form those may take isn’t clear. All seven planets are close in size to the Earth, with some of them in the star’s habitable zone, where temperatures could allow liquid water on rocky surfaces.
For those who are hoping to find evidence of life somewhere else in the Solar System, there was some exciting news this week. Two moons, Europa and Enceladus, were already thought to be among the best places to search, since both have liquid water oceans beneath their outer icy shells. And now, new data from the Cassini spacecraft and the Hubble Space Telescope has increased the potential for some form of living organisms to be found.
Some great new views from the Cassini spacecraft of Saturn’s tiny moon Atlas were released today. Atlas is similar to another Saturnian “ravioli” or “flying saucer” moon, Pan – a central roughly spherical or oblate body with an unusual broad equatorial ridge. Like Pan, the ridge is thought to have formed from material coming from Saturn’s rings, and also like Pan, the ridge on Atlas appears very smooth, but is significantly larger. Atlas orbits just outside the outer edge of Saturn’s A ring and is very small, only about 15 kilometres (9.4 miles) across, but still larger than Pan.
For the first time, astronomers have detected an atmosphere surrounding a “super-Earth” exoplanet which is close in size to Earth, another key step towards finding a world similar in size to ours that is also habitable. It’s not Earth 2.0 just yet, but it’s another indication that we are getting closer to finding a world that reminds us of home.
It may not seem like it, but it is approaching two years now since New Horizons made its historic flyby of Pluto and its moons in July 2015. But even though it has been quiet since then, the mission continues, as the spacecraft is now preparing for its next flyby of another Kuiper Belt Object (KBO) on Jan. 1, 2019 – and now New Horizons has reached the halfway point between Pluto and the next target, called 2014 MU69. It’s another major milestone for a mission that gave us our first close-up views of the Pluto system, and revealed worlds utterly alien and unique in the Solar System.
The search for a possible ninth planet in our Solar System has intensified in recent months, with more astronomers as well as amateurs joining in the hunt. Previous studies have hinted at its existence, but actually finding it has remained an elusive task. Now, astronomers from The Australian National University (ANU) are investigating four unknown objects in the outer Solar System that could be viable candidates for the mystery planet.