A Galactic Merger


ngc2207Over next couple of billion years, these two spiral galaxies will end up in a complete galactic merger—the two galaxies will become a single, larger one. They’re about 150 million light-years away in the constellation of Canis Major (the Great Dog). The gravitational attraction of NGC 2207, the larger of the pair, is already stirring things up throughout its smaller partner, distorting IC 2163’s shape and throwing stars and gas into long streamers that extend over 100,000 light-years. However, most of the space between stars in a galaxy is empty. When these galaxies collide, almost none of the stars in them will crash into another star.

Image Credit: ESO

The Twin Jet Nebula


The Twin Jet NebulaThis cosmic butterfly is called the Twin Jet Nebula. It’s a planetary nebula but not just any planetary nebula—it’s a bipolar nebula.

An ordinary planetary nebulae have one star at its center. A bipolar nebulae has a binary star system. The wings of the Twin Jet Nebula are thought to be caused by the motion of its two central stars around each other. As the dying main star and its white dwarf companion orbit around their common center of mass, the ejected gas from the dying star is pulled into the two lobes. The two stars at the heart of the nebula circle one another about every 100 years. This rotation not only forms the wings of the butterfly and the two jets, it also allows the white dwarf to strip gas from its larger companion which then forms a large disc of material around the stars extending out for billions of kilometers, up to 15 times the orbit of Pluto. Even though that disk is of huuge, it is still too small to be seen on the image taken by Hubble.

Image Credit: ESA / NASA

A Mountain on Ceres


MountainThe Dawn spacecraft has returned images of this tall, conical mountain on Ceres. The mountain is located in the southern hemisphere and is about 6 km high. Its perimeter is sharply defined, and there almost no accumulated debris at the base of the brightly streaked slope.

This image was taken from an altitude of 1470 km. Dawn will spend the next couple of months mapping the planet from that height. Next, it will move to within 375 km of the surface.

BTW, there’s still no word on those bright spots.

Image Credit: NASA