A Sonic Boom
21.02.2001

Many people have heard a sonic boom, but few have seen one. When an airplane travels at a speed faster than sound, density waves of sound emitted by the plane cannot precede the plane, and so accumulate in a cone behind the plane.

The Sun Spews X-rays
4.10.1995

Our Sun is really very hot. The Sun's outer atmosphere is so hot that it emits much light in the X-ray band, which was unexpected. X-rays are usually emitted from objects having a temperature in the millions of degrees, not the mere thousands of degrees of the Sun's surface.

Solstice Celebration
20.06.2004

Season's greetings! Today or tomorrow, depending on your time zone, the Sun reaches its northernmost point in planet Earth's sky marking a season change and the first solstice of the year 2004. In celebration, consider this delightfully detailed, brightly colored image of the active Sun.

Saturnian Aurora
23.01.1999

Girdling the second largest planet in the Solar System, Saturn's Rings are one of the most spectacular sights for earthbound telescopes. This image from the orbiting Hubble Space Telescope's STIS instrument, offers a striking view of another kind of ring around Saturn - pole encircling rings of ultraviolet aurora.

Red Saturn
10.02.2005

This strange, false-color image of otherwise familiar planet Saturn shows temperature changes based on thermal infrared emission in the gas giant's atmosphere and rings. Recorded from the Keck I telescope on Mauna Kea, the sharp, ground-based picture of Saturn's southern hemisphere is a mosaic of 35 images.

Unusual Aurora During Solar Wind Dropout
23.12.1999

On May 10, for some unknown reason, the Solar Wind virtually stopped. Normally our Sun emits a wind of between five and ten energetic particles per cubic centimeter moving outward at about 500 kilometers per second.

A Total Lunar Eclipse Over North Carolina
26.08.2007

This coming Tuesday, our Moon will appear to disappear. A similar total lunar eclipse is seen above in a time lapse image captured in 2003 over North Carolina, USA. As the Earth moves between the Moon and the Sun, the Earth's shadow fell on the moon, making it quite dark.

Night of the Long Leonid
22.11.2012

A cosmic grain of sand left the long and colorful trail across this all-sky view. Its grazing impact with planet Earth's atmosphere began at 71 kilometers per second. With the Milky Way stretching...

Time Lapse Auroras Over Norway
29.12.2013

Sometimes, after your eyes adapt to the dark, a spectacular sky appears. Such was the case in 2011 March when one of the largest auroral displays in recent years appeared over northern locations like the border between Norway and Russia.

Halley Dust and Milky Way
9.05.2014

The early morning hours of May 6 were moonless when grains of cosmic dust streaked through dark skies. Swept up as planet Earth plows through dusty debris streams left behind periodic Comet Halley, the annual meteor shower is known as the Eta Aquarids.