Rotating a Galaxy

This animation illustrates the rotation rate of the Large Magellanic Cloud (LMC). Hubble Space Telescope observations have been used to determine that the central part of the LMC completes a rotation every 250 million years. It takes more than 10 million years for even the small amount of rotation illustrated in this video.

Video Credit: NASA


This video takes us around the Moon and shows how it is illuminated not only by the brilliant light of the Sun but also by light reflected from the Earth. The trip starts on the side facing away from Earth where part of the surface is brightly illuminated by the Sun but the rest is totally dark. Moving around the Moon, the Earth rises, and its reflected bluish light illuminates the Moon’s surface. This dull glow is the earthshine. (You can clearly see it from Earth when the Moon appears as a crescent in the evening or morning sky.) When the Sun emerges from behind the Moon, the brilliant crescent is seen, but the earthshine is still faintly visible.

Video Credit: ESO

Tycho’s Supernova

In 1572, Danish astronomer Tycho Brahe was among those who reported a new bright object in the constellation Cassiopeia. We now know that Tycho’s new star was not new at all. It was a supernova, a stellar explosion so bright that it can outshine the light from rest of the galaxy. This particular supernova was a Type Ia, which occurs when a white dwarf star pulls material from, or merges with, a nearby companion star until a violent explosion is triggered. The white dwarf star is obliterated, sending its debris hurtling into space.

This false color image of the remnant of Tycho’s supernova combines from the Chandra X-ray Observatory with optical data from the Digitized Sky Survey. It uses date from two narrow ranges of X-ray energies to isolate material (silicon, colored red) moving away from Earth, and moving towards us (also silicon, colored blue). The other colors in the image (yellow, green, blue-green, orange and purple) show a broad range of different energies and elements, and a mixture of directions of motion.

Image Credit: X-ray—NASA / CXC / RIKEN & GSFC / T. Sato et al; Optical: DSS

NGC 613

A spiral galaxy’s brights and darksNGC 613 is a barred spiral galaxy about 65 million light-years away in the constellation of The Sculptor. It’s core looks bright and uniformly white in this image as a result of the combined light shining from the high concentration of stars packed into the core, but a massive black hole lurks at the center of this brilliance. Its mass is estimated at about 10 times that of the Milky Way’s supermassive black hole, and it is consuming stars, gas, and dust. As matter descends into the black hole’s, it radiates energy, but when looking at the galaxy in the optical and infrared wavelengths used to take this image, there is no trace of its dark heart.

Image Credit: ESA / NASA