Daytime Moon Meets Morning Star
16.11.2023

Venus now appears as Earth's brilliant morning star, shining above the southeastern horizon before dawn. For early morning risers, the silvery celestial beacon rose predawn in a close pairing with a waning crescent Moon on Thursday, November 9.

Julius Caesar and Leap Days
29.02.2016

Today, February 29th, is a leap day - a relatively rare occurrence. In 46 BC, Julius Caesar, featured here in a self-decreed minted coin, created a calendar system that added one leap day every four years.

The Largest Rock Known
2.01.2000

There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid, moon, and comet nucleus. It is larger than any other rocky planet. (Nobody knows...

A Solstice Sunset Self Portrait
21.06.2013

Today, the solstice is at 05:04 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth's sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south.

A Delta Rocket Launches
13.12.1995

A Delta rocket is seen being launched in 1988. In use since 1960, Delta rockets have been launched successfully over 200 times. Scientific satellites placed into orbit by a Delta rocket include IUE, COBE, LAGEOS-I, ROSAT, EUVE, GEOTAIL, and WIND.

Daytime Moon Meets Morning Star
10.12.2015

Venus now appears as Earth's brilliant morning star, standing in a line-up of planets above the southeastern horizon before dawn. For most, the silvery celestial beacon rose predawn in a close pairing with an old crescent Moon on Monday, December 7.

The View Near a Black Hole
23.03.2014

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.

At the Center of the Milky Way
11.12.2008

At the center of our Milky Way Galaxy lies a supermassive black hole. Once a controversial claim, this conclusion is now solidly based on 16 years of observations that map the orbits of 28 stars very near the galactic center.

GRO J165540: Evidence for a Spinning Black Hole
26.12.2004

In the center of a swirling whirlpool of hot gas is likely a beast that has never been seen directly: a black hole. Studies of the bright light emitted by the swirling gas frequently indicate not only that a black hole is present, but also likely attributes.

Retrograde Mars
13.06.2010

Why would Mars appear to move backwards? Most of the time, the apparent motion of Mars in Earth's sky is in one direction, slow but steady in front of the far distant stars. About every two years, however, the Earth passes Mars as they orbit around the Sun.