A Backward Sunspot and the New Solar Cycle
30.08.2006

Why is sunspot 905 backwards? Perhaps it is a key marker for the beginning of a new magnetic cycle on our Sun. Every 11 years, our Sun goes through a magnetic cycle, at the end of which its overall magnetic orientation is reversed.

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...

Dark Terrain on Saturn s Iapetus
3.01.2006

Why are vast sections of Iapetus as dark as coal? No one knows for sure. Iapetus, the third largest moon of Saturn, was inspected again as the Saturn-orbiting robot Cassini spacecraft swooped past the enigmatic world again late last year.

ISS Transits Mars
23.09.2020

Yes, but have you ever seen the space station do this? If you know when and where to look, watching the bright International Space Station (ISS) drift across your night sky is a fascinating sight -- but not very unusual.

WR 104: A Pinwheel Star System
3.06.2014

Might this giant pinwheel one-day destroy us? Probably not, but investigation of the unusual star system Wolf-Rayet 104 has turned up an unexpected threat. The unusual pinwheel pattern has been found to be created by energetic winds of gas and dust that are expelled and intertwine as two massive stars orbit each other.

A Distant Cluster of Galaxies
7.12.1997

In this 1994 Hubble Space Telescope photograph, every bright object is a galaxy. Oddly - most of them are spiral galaxies. This rich cluster of galaxies, named CL 0939+4713, is almost half way across the visible universe.

Iapetus: Saturn's Disappearing Moon
15.10.1995

Iapetus has an unusual surface, one half of which is very dark, the other half very light. This caused it's discoverer Cassini to remark that Iapetus could only be seen when on one side of Saturn but not the other. The reason for the difference between hemispheres is presently unknown.

Circling a Black Hole at its Photon Sphere
2.07.2013

What would it look like to go right up to a black hole? One particularly interesting place near a black hole is its photon sphere, where photons can orbit in circles, a sphere 50 percent further out than the event horizon.

The GRB 110328A Symphony
19.04.2011

A symphony of planet-wide observations began abruptly on March 28 when the Earth-orbiting Swift satellite detected a burst of high-frequency gamma-rays from GRB 110328A. When the same source flared again after a 45 minute pause it was clear this event was not a typical gamma-ray burst.

Dark Bok Globules in IC 2944
29.12.1996

The dark spots in the above picture are not photographic defects but an unusual type of interstellar cloud known as a Bok globule. Bok globules, named after astronomer Bart Bok who studied them extensively, are small dark clouds made of gas and dust that are typically condensing to form a