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.

An Extrasolar Planet?
29.05.1998

This infrared Hubble Space Telescope view may contain the first ever direct image of a planet outside our own solar system. The picture shows a very young double star located about 450 light-years away toward the constellation of Taurus.

Water Discovered on the Moon
28.09.2009

Water has been discovered on the surface of the Moon. No lakes have been found, but rather NASA's Moon Mineralogy Mapper aboard India's new Chandrayaan-1 lunar orbiter radios back that parts of the Moon's surface absorb a very specific color of light identified previously only with water.

Cygnus X: The Inner Workings of a Nearby Star Factory
18.01.2012

How do stars form? To help study this complex issue, astronomers took a deep infrared image of Cygnus X, the largest known star forming region in the entire Milky Way Galaxy. The above recently-released...

Active Galaxy Centaurus A
10.01.2008

A mere 11 million light-years away, Centaurus A is a giant elliptical galaxy - the closest active galaxy to Earth. This remarkable composite view of the galaxy combines image data from the x-ray ( Chandra), optical(ESO), and radio(VLA) regimes.

Nearby Cepheid Variable RS Pup
29.08.2018

In the center is one of the most important stars on the sky. This is partly because, by coincidence, it is surrounded by a dazzling reflection nebula. Pulsating RS Puppis, the brightest star in the image center, is some ten times more massive than our Sun and on average 15,000 times more luminous.

APOD: 2024 January 3 Б A SAR Arc from New Zealand
3.01.2024

What is that unusual red halo surrounding this aurora? It is a Stable Auroral Red (SAR) arc. SAR arcs are rare and have only been acknowledged and studied since 1954. The featured wide-angle photograph...

Comet Tsuchinshan ATLAS Flys Away
19.10.2024

These six panels follow daily apparitions of comet C/2023 A3 Tsuchinshan-ATLAS as it moved away from our fair planet during the past week. The images were taken with the same camera and lens at the indicated dates and locations from California, planet Earth.

Hubble s Andromeda Galaxy Mosaic
21.02.2025

The largest photomosaic ever assembled from Hubble Space Telescope image data is a panoramic view of our neighboring spiral Andromeda Galaxy. With 600 overlapping frames assembled from observations made from July 2010 to December 2022, the full Hubble Andromeda Galaxy mosaic spans almost six full moons across planet Earth's sky.

Neptune: Once Around
14.07.2011

Neptune rotates once on its axis in about 16 hours. So, spaced about 4 hours apart these 4 images of the solar system's most distant gas giant cover one Neptune day. Recorded...