Is there an ocean below Sputnik basin on Pluto? The unusually smooth 1000-km wide golden expanse, visible in the featured image below from New Horizons, appears segmented into convection cells. But how was this region created?
One hypothesis now holds the answer to be a great impact that stirred up an underground ocean of salt water roughly 100-kilometers thick. The featured image of Sputnik Planum, part of the larger heart-shaped Tombaugh Regio, was taken last July and shows true details in exaggerated colors.
Although the robotic New Horizons spacecraft is off on a new adventure, continued computer-modeling of this surprising surface feature on Pluto is likely to lead to more refined speculations about what lies beneath.
Image Credit: NASA, Johns Hopkins U./APL, Southwest Research Inst.
The Porpoise Galaxy from Hubble
What’s happening to this spiral galaxy? Just a few hundred million years ago, NGC 2936, the upper of the two large galaxies shown, was likely a normal spiral galaxy — spinning, creating stars — and minding its own business.
But then it got too close to the massive elliptical galaxy NGC 2937 below and took a dive. Dubbed the Porpoise Galaxy for its iconic shape, NGC 2936 is not only being deflected but also being distorted by the close gravitational interaction. A burst of young blue stars forms the nose of the porpoise toward the left of the upper galaxy, while the center of the spiral appears as an eye.
Alternatively, the galaxy pair, together known as Arp 142, look to some like a penguin protecting an egg. Either way, intricate dark dust lanes and bright blue star streams trail the troubled galaxy to the lower right. The above image showing Arp 142 in unprecedented detail was taken by the Hubble Space Telescope.
Arp 142 lies about 300 million light years away toward the constellation, coincidently, of the Water Snake (Hydra). In a billion years or so the two galaxies will likely merge into one larger galaxy.
Image Credit: NASA, ESA, and The Hubble Heritage Team (STSci/AURA)