Mercury and the Quiet Sun
13.11.2019

On November 11, 2019 the Sun was mostly quiet, experiencing a minimum in its 11 year cycle of activity. In fact, the only spot visible was actually planet Mercury, making a leisurely 5 1/2 hour transit in front of the calm solar disk.

Extra Solar Planetary Atmosphere Detected
27.11.2001

By directly detecting the atmosphere of a planet outside our Solar System, humanity has taken another small step toward finding extraterrestrial life. The unexpected detection by David Charbonneau (Caltech) and associates came from Hubble Space Telescope observations of Sun-like star HD 209458.

Planetary Systems Now Forming in Orion
6.12.1996

How do planets form? Astronomers are finding out by studying one of the most interesting of all astronomical nebulae known, the Great Nebula in Orion. Insets to above mosaic show several planetary systems in formation. The bottom left insert shows the relative size of our own Solar System. The Orion Nebula contains many stellar nurseries.

Shapley 1: An Annular Planetary Nebula
25.06.2000

What happens when a star runs out of nuclear fuel? The center condenses into a white dwarf while the outer atmospheric layers are expelled into space and appear as a planetary nebula. This particular planetary nebula, designated Shapley 1 after the famous astronomer Harlow Shapley, has a very apparent annular ring like structure.

Sizzling Io
6.07.1998

What's cooking on Io? This active moon of Jupiter is marked with volcanoes spewing lava that is now known to be hotter than any lava on Earth. Above is the highest resolution color-enhanced image yet composed of the most active surface in our Solar System. Features as small as three kilometers are visible.

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.

The Sun Puffs
11.04.1997

The Earth has once again endured a burst of particles from the Sun. The latest storm, which began Monday, was one of the best documented solar storms to date. At 10 am (EDT) ground...

APOD: 2024 May 26 Б A Solar Filament Erupts
25.05.2024

What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space, producing an energetic coronal mass ejection (CME).

Shapley 1: An Annular Planetary Nebula
14.02.1997

What happens when a star runs out of nuclear fuel? The center condenses into a white dwarf while the outer atmospheric layers are expelled into space and appear as a planetary nebula. This particular planetary nebula, designated Shapley 1 after the famous astronomer Harlow Shapley, has a very apparent annular ring like structure.

The Case of the Missing Aurora
21.10.1998

Sometimes, near midnight, auroras suddenly stop. Nobody knows why. This nightside gap in aurora was confirmed recently by D. Chua (U. Washington) and colleagues in data from the Ultraviolet Imager onboard the Polar spacecraft.