SN 1006: Pieces of the Cosmic Ray Puzzle
1.12.2000

Research balloon flights conducted in 1912 by Austrian physicist Victor Hess revealed that the Earth was constantly bombarded by high energy radiation from space - which came to be called "Cosmic Rays". What are Cosmic Rays and where do they come from?

Mars Then and Now
11.11.2003

Does Mars have canals? A hot debate topic of the late 1800s, several prominent astronomers including Percival Lowell not only claimed to see an extensive system of long straight canals on Mars, but used them to indicate that intelligent life exists there.

Rumors of a Strange Universe
26.02.2004

Only a few short years ago, when the APOD editors were in graduate school, the pervasive, cosmic Dark Energy was not even seriously discussed. Of course, it now appears that this strange energy dominates the cosmos (as well as lectures on cosmology) and provides a repulsive force accelerating the large scale expansion of the Universe.

CMBR Dipole: Speeding Through the Universe
8.10.2006

Our Earth is not at rest. The Earth moves around the Sun. The Sun orbits the center of the Milky Way Galaxy. The Milky Way Galaxy orbits in the Local Group of Galaxies. The Local Group falls toward the Virgo Cluster of Galaxies.

The Comets Of SOHO
24.02.2000

After four years of successful sun-gazing, the space-based SOlar and Heliospheric Observatory (SOHO) has also become the most successful comet-hunter in history, racking up 102 new comets. Above are examples of SOHO's comet discoveries imaged by LASCO, an on-board coronagraph.

Flaming Star Nebula
30.11.2016

A runaway star lights the Flaming Star Nebula in this cosmic scene. Otherwise known as IC 405, the Flaming Star Nebula's billowing interstellar clouds of gas and dust lie about 1,500 light-years away toward the constellation of Auriga.

Parker vs Perseid
15.08.2018

The brief flash of a bright Perseid meteor streaks across the upper right in this composited series of exposures made early Sunday morning near the peak of the annual Perseid meteor shower.

Lunar Eclipse over a Skyscraper
21.11.2021

Why is the Moon on top of this building? Planning. It took the astrophotographer careful planning -- including figuring out exactly where to place the camera and exactly when to take the shot -- to create this striking superposition.

SGR 1900+14 : Magnetar
3.09.1998

On August 27th an intense flash of X-rays and gamma-rays swept through our Solar System. Five spacecraft of the Third InterPlanetary gamma-ray burst Network, Ulysses, WIND, RXTE, NEAR, and BeppoSAX, recorded the high energy...

Star Forming Region LH 95
11.03.2008

How do stars form? To better understand this complex and chaotic process, astronomers used the Hubble Space Telescope to image in unprecedented detail the star forming region LH 95 in the nearby Large Magellanic Cloud galaxy.