Coronal Holes on the Sun
18.03.2003

The ominous, dark shapes haunting the left side of the Sun are coronal holes -- low density regions extending above the surface where the solar magnetic field opens freely into interplanetary space. Studied extensively from...

Four X-class Flares
16.05.2013

Swinging around the Sun's eastern limb on Monday, a group of sunspots labeled active region AR1748 has produced the first four X-class solar flares of 2013 in less than 48 hours. In time sequence clockwise from the top left, flashes from the four were captured in extreme ultraviolet images from the Solar Dynamics Observatory.

Airglow, Gegenschein, and Milky Way
20.04.2013

As far as the eye could see, it was a dark night at Las Campanas Observatory in the southern Atacama desert of Chile. But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds.

Solar Shock Wave
30.04.1999

On September 24, 1997 a shock wave blasted across the surface of the sun at speeds of 250 to 600 kilometers per second. On planet Earth, observer Barry Reynolds photographed the expanding shock front (left) in the light emitted by hydrogen atoms at the solar surface.

Flare Well AR 10486
6.11.2003

Almost out of view from our fair planet, rotating around the Sun's western edge, giant sunspot region AR 10486 lashed out with another intense solar flare followed by a large coronal mass ejection (CME) on Tuesday, November 4th at about 1950 Universal Time.

AR9077: Solar Magnetic Arcade
20.07.2000

On July 14th, solar active region 9077 (AR9077) produced a massive flare. The event also blasted an enormous cloud of energetic charged particles toward planet Earth, triggering magnetic storms and dramatic auroral displays. This striking close-up of AR9077 was made by the orbiting TRACE satellite shortly after the flare erupted.

Maximum Sun
1.03.2001

Astronomers recently witnessed an astounding, large scale solar event as the Sun's north and south magnetic poles changed places! But, this complete solar magnetic field flip was actually anticipated. It occurs every 11 years during the maximum of the solar activity cycle.

Layers of a Total Solar Eclipse
27.09.2017

Neither rain, nor snow, nor dark of night can keep a space-based spacecraft from watching the Sun. In fact, from its vantage point 1.5 million kilometers sunward of planet Earth, NASA's SOlar Heliospheric Observatory (SOHO) can always monitor the Sun's outer atmosphere, or corona.

Lasers in Eta Carinae
11.01.1996

Have you heard about the great LASER light show in the sky? Well, nobody had until it was announced just yesterday by a team led by K. Davidson (U. Minnesota) and S. Johansson (U. Lund).

Lasers in Eta Carinae
29.11.1997

Have you heard about the great LASER light show in the sky? A team led by K. Davidson (U. Michigan) and S. Johansson (U. Lund) discovered that the chaotically variable star Eta Carinae emits ultraviolet light in such a narrow band that it is most probably LASER light!