Julius Caesar and Leap Days
29.02.1996

Today, February 29th, is a leap day - a relatively rare occurrence. Advised by Alexandrian astronomer Sosigenes, Roman dictator Julius Caesar, pictured above in a self-decreed minted coin, created a calender system in 46 BC that contained one leap day every four years.

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.

APOD: 2023 September 20 Б Methane Discovered on Distant Exoplanet
20.09.2023

Where else might life exist? One of humanity's great outstanding questions, locating planets where extrasolar life might survive took a step forward in 2019 with the discovery of a significant amount of water vapor in the atmosphere of distant exoplanet K2-18b.

Fireball!
26.02.1996

On rare but spectacular occasions, fireballs, meteors brighter than the brightest stars, flash through the heavens - sometimes making audible sounds and occasionally surviving to strike the Earth's surface. The path of one such...

Comet Heart and Soul
23.08.2018

The greenish coma of comet 21P/Giacobini-Zinner stands out at the left of this telephoto skyscape spanning over 10 degrees toward the northern constellations Cassiopeia and Perseus. Captured on August 17, the periodic comet is the known parent body of the upcoming Draconid meteor shower.

Comet Hale-Bopp Returns
6.02.1997

Comet Hale-Bopp has returned from behind the Sun. In December and early January, Comet Hale-Bopp was too near the Sun to be easily visible from Earth. Now the comet graces the morning sky and is visible from dark locations even without binoculars.

Shuttle Plume Shadow Points to Moon
3.06.2007

Why would the shadow of a space shuttle launch plume point toward the Moon? In early 2001 during a launch of Atlantis, the Sun, Earth, Moon, and rocket were all properly aligned for this photogenic coincidence.

Waterway to Orbit
13.02.2010

The 32nd shuttle mission to the International Space Station, STS-130, left planet Earth on February 8. Its early morning launch to orbit from Kennedy Space Center's pad 39A followed the long, graceful, eastward arc seen in this 2 minute time exposure.

Milky Way in Moonlight
23.04.2016

A waning crescent moon, early morning twilight, and Al Hamra's city lights on the horizon can't hide the central Milky Way in this skyscape from planet Earth. Captured in a single exposure...

Magnetars In The Sky
26.11.2004

Indicated on this infrared image of the galactic center region are positions of candidate magnetars -- believed to be the strongest magnets in the galaxy. Classified by observers as Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), these cosmic powerhouses are likely city-sized, spinning, highly-magnetized neutron stars. How strong is a magnetar's magnetic field?