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.

Gas and Snow Jets from Comet Hartley 2
23.11.2010

Unusual jets have been discovered emanating from Comet Hartley 2. The EPOXI spacecraft imaged the jets in unprecedented detail during its flyby of the comet earlier this month. Pictured above, sun-illuminated jets shoot away from the two-kilometer long decaying iceberg that orbits the Sun between Earth and Jupiter.

Columbia Waits, Discovery Launches
8.08.1995

Space Shuttle Discovery launches while the Space Shuttle Columbia is readied for a future mission. Space shuttles are launched from the Kennedy Space Center in Florida. At this date there are four operating space shuttles: Atlantis, Columbia, Discovery, and Endeavour. This mission is most famous for carrying the Hubble Space Telescope into orbit.

A Sudden Jet on Comet 67P?
18.11.2015

There she blows! A dramatic demonstration of how short-lived some comet jets can be was documented in late July by the robotic Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko. The featured animation depicts changes in the rotating comet with three illuminating stills.

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.

GW170817: A Spectacular Multiradiation Merger Event Detected
16.10.2017

Both gravitational and electromagnetic radiations have been detected in rapid succession for an explosive merging event for the first time. Data from the outburst fit well with a spectacular binary neutron-star death-spiral. The explosive episode was seen on August 17 in nearby NGC 4993, an elliptical galaxy only 130 million light years distant.

Full Moonrise
5.05.2012

Rising as the Sun sets, tonight's Full Moon could be hard to miss. Remarkably, its exact full phase (May 6 03:36 UT) will occur less than two minutes after it reaches perigee, the closest point to Earth in the Moon's orbit, making it the largest Full Moon of 2012.

Unexpected X Rays from Perseus Galaxy Cluster
2.01.2018

Why does the Perseus galaxy cluster shine so strangely in one specific color of X-rays? No one is sure, but a much-debated hypothesis holds that these X-rays are a clue to the long-sought identity of dark matter.

Rhea: Saturn's Second Largest Moon
8.06.2003

Rhea is the second largest moon of Saturn, behind Titan, and the largest without an atmosphere. It is composed mostly of water ice, but has a small rocky core. Rhea's rotation and orbit are locked together (just like Earth's Moon) so that one side always faces Saturn.

The GRB 110328A Symphony
19.04.2011

A symphony of planet-wide observations began abruptly on March 28 when the Earth-orbiting Swift satellite detected a burst of high-frequency gamma-rays from GRB 110328A. When the same source flared again after a 45 minute pause it was clear this event was not a typical gamma-ray burst.