The Cosmic X-Ray Background
9.11.2000

Early on, x-ray satellites revealed a surprising cosmic background glow of x-rays and astronomers have struggled to understand its origin. Now, peering through a hole in the obscuring gas and dust...

Southern Cross over Chilean Volcano
25.01.2021

Have you ever seen the Southern Cross? This famous four-star icon is best seen from Earth's Southern Hemisphere. The featured image was taken last month in Chile and captures the Southern Cross just to the left of erupting Villarrica, one of the most active volcanos in our Solar System.

New Horizons Passes Pluto and Charon
14.07.2015

Will the New Horizons spacecraft survive its closest approach to Pluto and return useful images and data? Humanity will know in a few hours. Regardless of how well it functions, New Horizon's rapid...

Quadruple Lunar Halo Over Winter Road
2.01.2022

Sometimes falling ice crystals make the atmosphere into a giant lens causing arcs and halos to appear around the Sun or Moon. One Saturday night in 2012 was just such a time near Madrid, Spain, where a winter sky displayed not only a bright Moon but four rare lunar halos.

Rotating Asteroid Bennu from OSIRIS REx
13.11.2018

Could this close-by asteroid ever hit the Earth? Eventually yes -- but probably not for a very long time, even though the asteroid is expected to pass inside the orbit of the Moon next century.

Earth Nears Asteroid Toutatis
20.01.1997

On November 29, 1996 the Earth came within 3.3 million miles of the asteroid Toutatis. Above is a computer simulated picture of this spectacle from the surface of Toutatis (a 2.5 degree field of view looking toward Earth). In Earth's sky, Toutatis appeared only as a faint object moving against a background of stars.

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.

Plasma Jets from Radio Galaxy Hercules A
5.12.2012

Why does this galaxy emit such spectacular jets? No one is sure, but it is likely related to an active supermassive black hole at its center. The galaxy at the image center, Hercules A, appears to be a relatively normal elliptical galaxy in visible light.

The Sun Rotating
12.03.2014

Does the Sun change as it rotates? Yes, and the changes can vary from subtle to dramatic. In the above time-lapse sequences, our Sun -- as imaged by NASA's Solar Dynamics Observatory -- is shown rotating though the entire month of January.

APOD: 2020 August 19 Б The Sun Rotating
19.08.2020

Does the Sun change as it rotates? Yes, and the changes can vary from subtle to dramatic. In the featured time-lapse sequences, our Sun -- as imaged by NASA's Solar Dynamics Observatory -- is shown rotating though an entire month in 2014.