APOD: 2006 September 28- RCW 86: Historical Supernova Remnant
28.09.2006

In 185 AD, Chinese astronomers recorded the appearance of a new star in the Nanmen asterism - a part of the sky identified with Alpha and Beta Centauri on modern star charts. The new star was visible for months and is thought to be the earliest recorded supernova.

NGC 253: X Ray Zoom
7.06.2001

Astronomers now report that Chandra X-ray Observatory observations of galaxies known to be frantically forming stars show that these galaxies also contain luminous x-ray sources -- thought to be intermediate mass black holes and immense clouds of superheated gas. Take the lovely island universe NGC 253 for example.

Caught in the Afterglow
24.11.2011

In this artist's illustration, two distant galaxies formed about 2 billion years after the big bang are caught in the afterglow of GRB090323, a gamma-ray burst seen across the Universe. Shining through...

NGC 4603 and the Expanding Universe
27.05.1999

NGC 4603, a galaxy with majestic spiral arms and intricate dust lanes, is 108 million light-years away. Its distance has been accurately measured by astronomers using one of the fundamental yardsticks of the extragalactic distance scale - pulsating variable stars known as Cepheids.

Julius Caesar and Leap Days
29.02.2024

In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long.

Giant Cluster Bends, Breaks Galaxy Images
24.04.1996

What are those strange blue objects? Many are images of a single, unusual, beaded, blue, ring-like galaxy which just happens to line-up behind a giant cluster of galaxies. Cluster galaxies here appear yellow and -- together with the cluster's dark matter -- act as a gravitational lens.

An Extrasolar Planet?
29.05.1998

This infrared Hubble Space Telescope view may contain the first ever direct image of a planet outside our own solar system. The picture shows a very young double star located about 450 light-years away toward the constellation of Taurus.

Cygnus X: The Inner Workings of a Nearby Star Factory
18.01.2012

How do stars form? To help study this complex issue, astronomers took a deep infrared image of Cygnus X, the largest known star forming region in the entire Milky Way Galaxy. The above recently-released...

A Mystery in Gamma Rays
11.08.2001

Gamma rays are the most energetic form of light, packing a million or more times the energy of visible light photons. If you could see gamma rays, the familiar skyscape of steady stars would be replaced by some of the most bizarre objects known to modern astrophysics -- and some which are unknown.

Worlds of a Distant Sun: 47 Ursae Majoris b
5.10.1997

In the last few years, observational astronomy has given humanity evidence of the existence of worlds beyond the solar system. Solar-type stars are now inferred to harbor planets of approximately Jupiter mass - some residing in temperature zones which could conceivably support liquid water and therefore life!