A Yukon Aurora
8.10.2001

Last week was another good week for auroras. The story began about two weeks ago when two large Coronal Mass Ejections exploded off the Sun. Waves of elementary particles and ions swept out past the Earth on September 28 and 29, causing many auroras.

Lightning and the Space Shuttle
10.11.1995

There are many things about lightning that are not understood. Lightning has been seen in the atmospheres of Venus, Earth, Jupiter, and Saturn. A leading theory is that collisions of particles in clouds cause large areas of positive and negative charge.

Hale Bopp and the North American Nebula
9.10.1997

Comet Hale-Bopp's recent encounter with the inner Solar System allowed many breath-taking pictures. Above, Comet Hale-Bopp was photographed on March 8th in the constellation of Cygnus. Visible on the right in red is the North American Nebula, a bright emission nebula observable from a dark location with binoculars.

Comet Hale-Bopp's Developing Tail
14.03.1997

Comet Hale-Bopp is living up to its expectations. Besides the brightness of its coma, a comet is typically remembered by the length of its tails. As visible in the above picture taken last week, Comet Hale-Bopp's blue ion tail shows a dramatic extension, with current reports of about 20 degrees from dark locations.

X-Ray Earth
30.12.1996

The Earth glows in many kinds of light, including the energetic X-ray band. Actually, the Earth itself does not glow - only aurora produced high in the Earth's atmosphere. Above is the first picture of the Earth in X-rays, taken in March with the orbiting Polar satellite. Bright X-ray emission is shown in red.

A Solar Prominence Erupts
24.09.2001

Our Sun is still very active. Last year, our Sun went though Solar Maximum, the time in its 11-year cycle where the most sunspots and explosive activities occur. Sunspots, the Solar Cycle, and solar prominences are all caused by the Sun's changing magnetic field.

Comet Hale-Bopp Enters the Evening Sky
7.03.1997

You no longer have to wake-up early to see Comet Hale-Bopp. From many northern locations, you can now go outside just after sunset and see Comet Hale-Bopp above the north-western horizon. Both writer/editors of APOD are impressed by how bright Comet Hale-Bopp has become, and how easily visible it is.

Dragon Aurora over Norway
10.04.2018

What's that in the sky? An aurora. A large coronal hole opened last month, a few days before this image was taken, throwing a cloud of fast moving electrons, protons, and ions toward the Earth.

Comet 13P Olbers
28.06.2024

Not a paradox, Comet 13P/Olbers is returning to the inner Solar System after 68 years. The periodic, Halley-type comet will reach its next perihelion or closest approach to the Sun on June 30 and has become a target for binocular viewing low in planet Earth's northern hemisphere night skies.

Comet Pons-Brooks at Night
4.04.2024

In dark evening skies over June Lake, northern hemisphere, planet Earth, Comet 12P/Pons-Brooks stood just above the western horizon on March 30. Its twisted turbulent ion tail and diffuse greenish coma are captured in this two degree wide telescopic field of view along with bright yellowish star Hamal also known as Alpha Arietis.