Autumn and the Active Sun
23.09.1998

As the Sun heads South, crossing the celestial equator today at 1:37 a.m. Eastern Time, Autumn begins for Earth's Northern Hemisphere. This Autumnal Equinox finds an increasingly active Sun steadily approaching a solar cycle maximum expected around the year 2003.

Andromedas Core
27.12.2004

The center of the Andromeda galaxy is beautiful but strange. Andromeda, indexed as M31, is so close to our own Milky Way Galaxy that it gives a unique perspective into galaxy composition by allowing us to see into its core.

Fire on Earth
26.08.2018

Sometimes, regions of planet Earth light up with fire. Since fire is the rapid acquisition of oxygen, and since oxygen is a key indicator of life, fire on any planet would be an indicator of life on that planet.

APOD: 2024 September 22 Б Chicagohenge: Equinox in an Aligned City
22.09.2024

Chicago, in a way, is like a modern Stonehenge. The way is east to west, and the time is today. Today, and every equinox, the Sun will set exactly to the west, everywhere on Earth.

Betelgeuse, Betelgeuse, Betelgeuse
5.06.1999

Betelgeuse (sounds a lot like "beetle juice"), a red supergiant star about 600 light years distant, is seen in this Hubble Space Telescope image - the first direct picture of the surface of a star other than the Sun. While Betelgeuse is cooler than the Sun, it is more massive and over 1000 times larger.

Aurora Astern
10.02.2001

Sailing upside down, 115 nautical miles above Earth, the crew of the Space Shuttle Endeavour made this spectacular time exposure of the southern aurora (aurora australis) in October of 1994. Aurora, also known as the northern and southern lights, appear as luminous bands or streamers of light which can extend to altitudes of 200 miles.

The Leonid Meteor Shower (Tonight)
16.11.1996

Tonight thousands of icy rocks will hurl toward Earth in a fascinating display of light called the Leonid Meteor Shower. There is little danger - few will reach the ground. But this year's Leonids could be nothing compared to the Leonids in 1998.

Rafting for Solar Neutrinos
28.10.1997

Where have all the neutrinos gone? A long time passing since this question was first asked (decades) as increasingly larger and more diverse detectors sensitive to neutrinos from our Sun have found fewer than expected. But why?

The Crab Nebula from CFHT
28.01.2004

This is the mess that is left when a star explodes. The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments. The filaments are not only tremendously...

A Green Flash from the Sun
21.03.2004

Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood.