X-Ray Earth
16.09.2000

Above is a picture of the Earth in x-rays, taken in March of 1996 from the orbiting Polar satellite. Most of the planet is dark with superposed continent and coordinate grids, while the bright x-ray emission near the north pole is shown in red. Why does the Earth have an x-ray glow?

The Largest Rock Known
1.01.2000

There, that faint dot in the center - that's the largest rock known. It is larger than every known asteroid, moon, and comet nucleus. It is larger than any other rocky planet. (Nobody knows...

Lightning on Earth
18.08.2004

Nobody knows what causes lightning. It is known that charges slowly separate in some clouds causing rapid electrical discharges (lightning), but how electrical charges get separated in clouds remains a topic of much research.

A Colorful Aurora
1.09.1998

A solar storm overtook the Earth on August 26th. The Earth survived unscathed, as usual, although many northerners reported an impressive display of aurora. Many of these auroras changed rapidly, with patterns appearing and disappearing sometimes in less than a second. Out away from city lights, observers also reported an unusually spectacular array of colors.

The Sun Also Rises
24.10.1998

Sunrise seen from low Earth orbit by the shuttle astronauts can be very dramatic indeed ( and the authors apologize to Hemingway for using his title!). In this breathtaking view, the Sun is just visible...

El Nino Earth
11.11.1997

El Niño is a temporary global climate change resulting from unusually warm water in the central Pacific Ocean. El Niño can cause unusual or severe weather for some locations over the next few months.

The Earth and Moon from Mars
26.05.2003

What does Earth look like from Mars? The first image of Earth from the red planet was captured earlier this month by the camera onboard the Mars Global Surveyor spacecraft currently orbiting Mars. Features visible on Earth include the Pacific Ocean, clouds, much of South America, and part of North America.

The View from Everest
8.04.2007

What would it be like to stand atop the tallest mountain on Earth? To see a full panoramic vista from there, scroll right. Visible are snow peaked mountains near and far, tremendous cliffs, distant plateaus, the tops of clouds, and a dark blue sky. Mt.

Noctilucent Clouds
26.07.1999

Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above.

Noctilucent Clouds
19.06.2005

Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above.