Hubble Floats Free
6.03.1997

Why put observatories in space? Most telescopes are on the ground. On the ground, you can deploy a heavier telescope and upgrade it more easily. The trouble is that Earth-bound telescopes must look through the Earth's atmosphere.

Kepler s SNR from Chandra, Hubble, Spitzer
8.10.2004

Light from the stellar explosion that created this energized cosmic cloud was first seen on planet Earth in October 1604, a mere four hundred years ago. The supernova produced a bright new star in early 17th century skies within the constellation Ophiucus.

Comet Leonards Tail Wag
10.01.2022

Why does Comet Leonard's tail wag? The featured time-lapse video shows the ion tail of Comet C/2021 A1 (Leonard) as it changed over ten days early last month. The video was taken by NASA's Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft that co-orbits the Sun at roughly the same distance as the Earth.

Time Tunnel
6.09.2007

Spiky stars are nearby, but fuzzy galaxies are strewn far across the Universe in this cosmic view. Spanning about 1/2 degree on the sky, the pretty picture is the result of astronomer Johannes Schedler's project to look back in time, toward a quasar 12.7 billion light-years away.

The Gegenschein Over Chile
7.05.2008

Is the night sky darkest in the direction opposite the Sun? No. In fact, a rarely discernable faint glow known as the gegenschein (German for "counter glow") can be seen 180 degrees around from the Sun in an extremely dark sky. The gegenschein is sunlight back-scattered off small interplanetary dust particles.

Four X-class Flares
16.05.2013

Swinging around the Sun's eastern limb on Monday, a group of sunspots labeled active region AR1748 has produced the first four X-class solar flares of 2013 in less than 48 hours. In time sequence clockwise from the top left, flashes from the four were captured in extreme ultraviolet images from the Solar Dynamics Observatory.

LIGO Detects Gravitational Waves from Merging Black Holes
11.02.2016

Gravitational radiation has been directly detected. The first-ever detection was made by both facilities of the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Washington and Louisiana simultaneously last September. After numerous consistency checks, the resulting 5-sigma discovery was published today.

Airglow, Gegenschein, and Milky Way
20.04.2013

As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds.

Orions Belt Region in Gas and Dust
11.01.2022

You may have seen Orion's belt before -- but not like this. The three bright stars across this image are, from left to right, Mintaka, Alnilam, and Alnitak: the iconic belt stars of Orion.

The Colorful Clouds of Rho Ophiuchi
12.03.1996

The many spectacular colors of the Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the star rho Ophiuchi and nearby stars reflects more efficiently off this portion of the nebula than red light.