The Black Hole in the Milky Way
2.11.2012

At the center of our Milky Way Galaxy, a mere 27,000 light-years away, lies a black hole with 4 million times the mass of the Sun. Fondly known as Sagittarius A* (pronounced A-star)...

NGC 4696: Energy from a Black Hole
27.04.2006

In many cosmic environments, when material falls toward a black hole energy is produced as some of the matter is blasted back out in jets. In fact, such black hole "engines" appear to be the most efficient in the Universe, at least on a galactic scale.

JKCS041: The Farthest Galaxy Cluster Yet Measured
28.10.2009

What if we could see back to the beginning of the universe? We can -- since it takes the age of the universe for light to cross the universe. Peering at distant objects, therefore, tells us about how the universe used to be, even near its beginning.

Earth Nears Asteroid Toutatis
20.01.1997

On November 29, 1996 the Earth came within 3.3 million miles of the asteroid Toutatis. Above is a computer simulated picture of this spectacle from the surface of Toutatis (a 2.5 degree field of view looking toward Earth). In Earth's sky, Toutatis appeared only as a faint object moving against a background of stars.

Hubble's Constant And The Expanding Universe (I)
13.05.1996

Our Universe is expanding. Distant galaxies appear to recede from us at ever-increasing speeds. What is the rate of expansion? How long has it been expanding? What will be its ultimate fate? Two groups of astronomers are searching vigorously for answers to these fundamental questions using the Hubble Space Telescope (HST).

Rocket Launch as Seen from the Space Station
26.11.2018

Have you ever seen a rocket launch -- from space? A close inspection of the featured time-lapse video will reveal a rocket rising to Earth orbit as seen from the International Space Station (ISS).

Far Side of the Sun
3.05.2001

You may think it's impossible to see through the Sun, but maps of the Sun's far side are now made routinely by instruments on board the sun-staring SOHO spacecraft. This is one such map from April 12.

A Gegenschein Lunar Eclipse
14.10.2015

Is there anything interesting to see in the direction opposite the Sun? One night last month, there were quite a few things. First, the red-glowing orb on the lower right of the featured image is the full moon, darkened and reddened because it has entered Earth's shadow.

Pioneer 10: The First 7 Billion Miles
25.08.2001

Q: What was made by humans and is 7.3 billion miles away? A: Pioneer 10 -- and 1997 was the 25th anniversary of its launch. Almost 11 light-hours distant, Pioneer 10 is presently about twice as far from the Sun as Pluto, and bound for interstellar space at 28,000 miles per hour.

APOD: 2017 November 22 Oumuamua: Interstellar Asteroid
22.11.2017

Nothing like it has ever been seen before. The unusual space rock 'Oumuamua is so intriguing mainly because it is the first asteroid ever detected from outside our Solar System -- although likely many more are to follow given modern computer-driven sky monitoring.