Julius Caesar and Leap Days
29.02.2024

In 46 BC Julius Caesar reformed the calendar system. Based on advice by astronomer Sosigenes of Alexandria, the Julian calendar included one leap day every four years to account for the fact that an Earth year is slightly more than 365 days long.

Rigel Wide
7.04.2023

Brilliant, blue, supergiant star Rigel marks the foot of Orion the Hunter in planet Earth's night. Designated Beta Orionis, it's at the center of this remarkably deep and wide field of view.

Escape From The Sun
20.11.1997

Twisted magnetic fields arching from the solar surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the solar limb. On September 14, this...

A Solar Prominence from SOHO
16.04.2006

How can gas float above the Sun? Twisted magnetic fields arching from the solar surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the solar limb.

A Solar Prominence from SOHO
31.05.2009

How can gas float above the Sun? Twisted magnetic fields arching from the solar surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the solar limb.

A Visit from Atlantis
28.06.2007

This remarkable image of the space shuttle orbiter Atlantis docked with the International Space Station (ISS) was taken at a range of 190 nautical miles. To record the fast moving pair, last week astronomers...

Mars: A Mist In Mariner Valley
17.10.1997

An icy mist and late afternoon clouds cover much of this section of Valles Marineris on Mars. The Valles Marineris or Mariner Valley is a huge canyon system about 2,000 miles long and up to 5 miles deep.

Dwarf Planet, Bright Spot
14.05.2015

Now at Ceres, Dawn's camera recorded this closer view of the dwarf planet's northern hemisphere and one of its mysterious bright spots on May 4. A sunlit portrait of a small, dark...

The W in Cassiopeia
18.03.2016

A familiar, zigzag, W pattern in northern constellation Cassiopeia is traced by five bright stars in this colorful and broad mosaic. Stretching about 15 degrees across rich starfields, the celestial scene includes dark clouds, bright nebulae, and star clusters along the Milky Way. In yellow-orange hues Cassiopeia's alpha star Shedar is a standout though.

Space Station Lookout
10.04.2013

If you glanced out a side window of the International Space Station, what might you see? If you were Expedition 34 flight engineer Chris Hadfield, and you were looking out one of windows of Japan's Kibo Research Module on February 26, you might have seen the above vista.