Astronomy Picture Of the Day (APOD)Cassini Spacecraft Approaches Jupiter
A new spacecraft has entered the outer Solar System: Cassini. Launched in 1997 and bound for Saturn in 2004, Cassini sent back the above image last week while approaching the giant planet Jupiter. Cassini joins the Galileo spacecraft currently in orbit around Jupiter in studying the gas giant and its moons.
The Einstein Cross Gravitational Lens
Most galaxies have a single nucleus -- does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The central cloverleaf is rather light emitted from a background quasar.
A Polar Martian Dust Storm
On August 29, a large dust storm was photographed erupting out from the north polar cap of Mars. Such dust storms are not uncommon as summer advances in the north. In the above picture...
Earth's Richat Structure
What on Earth is that? The Richat Structure in the Sahara Desert of Mauritania is easily visible from space because it is nearly 50 kilometers across. Once thought to be an impact crater, the Richat Structure's flat middle and lack of shock-altered rock indicates otherwise.
Sputnik: Traveling Companion
Sputnik means "traveling companion". Despite the innocuous sounding name, the launch of the Earth's first "artificial moon", Sputnik 1, by the Soviet Union on October 4, 1957 shocked the free world, setting in motion events which resulted in the creation of NASA and the race to the Moon.
X-Rays From Sirius B
In visible light Sirius A (Alpha Canis Majoris) is the brightest star in the night sky, a closely watched celestial beacon throughout recorded history. Part of a binary star system only 8 light-years away, it was known in modern times to have a small companion star, Sirius B.
N81: Star Cradle in the SMC
This dramatic Hubble Space Telescope image captures the birth of a cluster of massive stars. The newborn stars are seen just as they emerge from their natal nebula. Only 12 light-years across, the nebula...
Barred Spiral Galaxy NGC 1300
NGC 1300 is a large spiral galaxy that appears as a flattened figure eight. A huge bar that spans over 150,000 light-years across the galaxy center dominates its appearance. The picturesque galaxy lies about 75 million light-years distant, so that light that we see now left during the age of the dinosaurs.
The dramatic rotation of the cloud-tops of Saturn every ten-hours is particularly evident from orbit around the gas giant planet. With a good enough telescope, however, such rotation is visible even from Earth, as shown by this time-lapse image sequence from the Hubble Space Telescope taken in November 1990.
Pangea Ultima: Earth in 250 Million Years
Is this what will become of the Earth's surface? The surface of the Earth is broken up into several large plates that are slowly shifting. About 250 million years ago, the plates...