COBE Dipole: Speeding Through the Universe
27.06.1999

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. The Local Group falls toward the Virgo Cluster of Galaxies.

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.

The Hubble Ultra Deep Field
9.03.2004

The above picture will be replaced later today (between 9 and 10 am EST) by the newly released Hubble Ultra Deep Field (HUDF). The HUDF is expected to be the deepest image of the universe ever taken in visible light.

Light from the First Stars
2.01.2007

What were the first stars like? No one is yet sure. Our Sun is not a first-generation star. It is not even second generation. The first stars to appear in the universe likely came and went about 13 billion years ago.

A Force from Empty Space: The Casimir Effect
17.12.2006

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

A Force from Empty Space: The Casimir Effect
1.08.2004

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

Galaxies in the GOODS
25.06.2003

This tantalizing view of galaxies scattered near and far is part of the Hubble Space Telescope's contribution to the GOODS - the Great Observatories Origins Deep Survey project. The GOODS' goal is to study...

Leonids Over Korean Observatory
12.12.2001

There were two peaks to this year's Leonid Meteor Shower. The first peak was best seen during the early morning hours of November 18 in North America, while the second peak, almost twice the intensity of the first, occurred eight hours later and was best seen from Asia.

Rumors of a Strange Universe
27.02.2004

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.

The NTT SUSI Deep Field
15.09.1998

What happens if you point a large telescope at nothing? The above New Technology Telescope SUSI Deep Field photograph isolated a small patch of sky picked to contain no bright objects at all.