Eclipsed Moonlight
21.06.2011

A celestial prelude to today's solstice, the June 15 total lunar eclipse was one of the longest in recent years. It was also one of the darkest, but not completely dark. Even during...

Earth, Clouds, Sky, Comet
3.04.1997

Does a comet's dust tail always orbit behind it? Since comets rotate, they shed gas and dust in all directions equally. Small ice and dust particles expelled by the comet, however, are literally pushed around by sunlight. The smaller the particle, the greater the effect.

Quadrantid Meteors through Orion
19.01.2020

Why are these meteor trails nearly parallel? Because they were all shed by the same space rock and so can be traced back to the same direction on the sky: the radiant of the Quadrantid Meteor Shower.

The Local Void in the Nearby Universe
5.08.2019

What does our region of the Universe look like? Since galaxies are so spread out over the sky, and since our Milky Way Galaxy blocks part of the distant sky, it has been hard to tell.

Hypatia of Alexandria
26.01.1999

Sixteen hundred years ago, Hypatia became one of the world's leading scholars in mathematics and astronomy. Hypatia's legendary knowledge, modesty, and public speaking ability flourished during the era of the Great Library of Alexandria.

Mars, Pleiades, and Andromeda over Stone Lions
12.10.2020

Three very different -- and very famous -- objects were all captured in a single frame last month. On the upper left is the bright blue Pleiades, perhaps the most famous cluster of stars on the night sky. The Pleiades (M45) is about 450 light years away and easily found a few degrees from Orion.

Stars Without Galaxies
18.01.2002

Galaxies are made up of stars, but are all stars found within galaxies? Using the Hubble Space Telescope, researchers exploring the Virgo Cluster of galaxies have found about 600 red giant stars adrift in intergalactic space. Above is an artist's vision of the sky from a hypothetical planet of such a lonely sun.

Planets in the West
24.06.2005

This weekend three planets will grace the western sky, forming a lovely trio easily visible shortly after sunset. Saturday evening in particular will find Saturn, Venus, and Mercury all within a 2 degree circle (about the size of your thumb held at arm's length) above the western horizon.

The Milky Way Over Paranal
22.01.2007

It's not the sky that's falling. More accurately, the Earth is rising. The Earth's rotation gives a continually changing view to all Earth observers, including those measuring the universe at the Paranal Observatory.

The Solstice Moon s Eclipse
22.12.2010

A big, bright, beautiful Full Moon slid into planet Earth's shadow early Tuesday morning. Remarkably, the total lunar eclipse coincided with the date of the December Solstice. During the eclipse, the best viewing...