Cassini Spacecraft Crosses Saturns Ring Plane
4.05.2005

If this is Saturn, where are the rings? When Saturn's "appendages" disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn's unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear.

Spicules: Jets on the Sun
1.11.2008

Imagine a pipe as wide as a state and as long as half the Earth. Now imagine that this pipe is filled with hot gas moving 50,000 kilometers per hour. Further imagine that this pipe is not made of metal but a transparent magnetic field.

Sun Halo over Sweden
31.12.2017

What's happened to the Sun? Sometimes it looks like the Sun is being viewed through a giant lens. In the featured video, however, there are actually millions of tiny lenses: ice crystals. Water may freeze in the atmosphere into small, flat, six-sided, ice crystals.

APOD: 2025 March 18 Б LDN 1235: The Shark Nebula
17.03.2025

There is no sea on Earth large enough to contain the Shark nebula. This predator apparition poses us no danger as it is composed only of interstellar gas and dust. Dark dust like that featured here is somewhat like cigarette smoke and created in the cool atmospheres of giant stars.

The Cepheids of M100
9.01.1996

Can this blinking star tell us how fast the universe is expanding? Many astronomers also believe it may also tell us the age of the universe! The photographed "Cepheid variable" star in M100 brightens and dims over the course of days as its atmosphere expands and contracts.

Trees, Stars, Aurora
9.02.2012

Have you ever seen an aurora? Auroras are occurring again with increasing frequency. With the Sun being unusually dormant over the past four years, the amount of Sun-induced auroras has been unusually low. More recently, however, our Sun has become increasingly active and exhibiting a greater abundance of sunspots, flares, and coronal mass ejections.

Ingenuity: A Mini Helicopter Now on Mars
1.03.2021

What if you could fly around Mars? NASA may have achieved that capability last month with the landing of Perseverance, a rover which included a small flight-worthy companion called Ingenuity, nicknamed Ginny. Even though...

APOD: 2023 September 24 Б A Ring of Fire Sunrise Solar Eclipse
23.09.2023

What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun.

APOD: 2023 December 27 Б Rainbow Aurora over Icelandic Waterfall
26.12.2023

Yes, but can your aurora do this? First, yes, auroras can look like rainbows even though they are completely different phenomena. Auroras are caused by Sun-created particles being channeled into Earth's atmosphere by Earth's magnetic field, and create colors by exciting atoms at different heights.

Huygens: Titan Descent Movie
21.01.2013

What would it look like to land on Saturn's moon Titan? The European Space Agency's Huygens probe set down on the Solar System's cloudiest moon in 2005, and a time-lapse video of its descent images was created.