NGC 5584: Expanding the Universe
30.03.2011

Big, beautiful NGC 5548 is more that 50,000 light-years across and lies 72 million light-years away toward the constellation Virgo. The winding spiral arms of this gorgeous island universe are loaded with luminous young star clusters and dark dust lanes. Still, for earthbound astronomers NGC 5548 is not just another pretty face-on spiral galaxy.

The Potsdam Gravity Potato
14.12.2014

Why do some places on Earth have higher gravity than others? Sometimes the reason is unknown. To help better understand the Earth's surface, sensitive measurments by the orbiting satellites GRACE and CHAMP were used to create a map of Earth's gravitational field.

APOD: 2025 April 27 Б IC 418: The Spirograph Nebula
27.04.2025

What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours.

A Fox Fur, a Unicorn, and a Christmas Tree
10.04.2012

What do the following things have in common: a cone, the fur of a fox, and a Christmas tree? Answer: they all occur in the constellation of the unicorn (Monoceros). Pictured above...

A Fox Fur, a Unicorn, and a Christmas Tree
4.01.2015

What do the following things have in common: a cone, the fur of a fox, and a Christmas tree? Answer: they all occur in the constellation of the unicorn (Monoceros). Pictured as a star...

Gamma-Ray Burster
19.03.1997

What and where are the Gamma-Ray Bursters? Since their discovery in the early 1970s, nobody has been able to explain the cause of mysterious flashes of gamma rays that come from seemingly random directions on the sky.

Aurora around Saturns North Pole
3.09.2018

Are Saturn's auroras like Earth's? To help answer this question, the Hubble Space Telescope and the Cassini spacecraft monitored Saturn's North Pole simultaneously during Cassini's final orbits around the gas giant in September 2017. During this time, Saturn's tilt caused its North Pole to be clearly visible from Earth.

Comet Leonard Closeup from Australia
12.01.2022

What does Comet Leonard look like up close? Although we can't go there, imaging the comet's coma and inner tails through a small telescope gives us a good idea. As the name...

IC 418: The Spirograph Nebula
7.09.2000

What is creating the strange texture of IC 418? Dubbed the Spirograph Nebula for its resemblance to drawings from a cyclical drawing tool, planetary nebula IC 418 shows patterns that are not well understood. Perhaps they are related to chaotic winds from the variable central star, which changes brightness unpredictably in just a few hours.

Mira: The Wonderful Star
5.05.2005

To seventeenth century astronomers, Omicron Ceti or Mira was known as a wonderful star - a star whose brightness could change dramatically in the course of about 11 months. Modern astronomers now recognize an entire class of long period Mira-type variables as cool, pulsating, red giant stars, 700 or so times the diameter of the Sun.