A Solar Filament Lifts Off
9.08.2000

Hot gas frequently erupts from the Sun. One such eruption produced the glowing filament pictured above, which was captured on July 19 by the Earth-orbiting TRACE satellite. The filament, although small compared...

APOD: 2025 November 17 Б Comet Lemmons Wandering Tail
17.11.2025

What has happened to Comet Lemmon's tail? The answer is blowing in the wind Б the wind from the Sun in this case. This continuous outflow of charged particles from...

Moonrise and Mountain Shadow
14.03.2020

What phase of the Moon is 3.14 radians from the Sun? The Full Moon, of course. Even though the Moon might look full for several days, the Moon is truly at its full phase when it is 3.14 radians (aka 180 degrees) from the Sun in ecliptic longitude.

Perihelion to Aphelion
8.07.2021

Aphelion for 2021 occurred on July 5th. That's the point in Earth's elliptical orbit when it is farthest from the Sun. Of course, the distance from the Sun doesn't determine the seasons.

A Martian Halloween
31.10.2005

From sunset to sunrise, an unusually bright yellowish orb will hang in the sky this Halloween: Mars. Yesterday, Earth passed Mars as they orbited the Sun, bringing Mars closer than it will be for the next thirteen years. Tonight though, Mars will be nearly as bright as last night, a beacon of extraterrestrial spookiness.

Large Eruptive Prominence Imaged by STEREO
18.04.2010

What's happened to our Sun? Last week, it produced one of the most power eruptive prominences ever seen. Pictured above, the prominence erupted in only a few hours and was captured in movie form by NASA's twin Sun-orbiting STEREO satellites.

Double Eruptive Prominences
18.04.2003

Lofted over the Sun on looping magnetic fields, large solar prominences are composed of relatively cool, dense plasma. When seen against the brilliant solar disk they appear as dark filaments, but these enormous magnetic...

High Noon Analemma Over Azerbaijan
14.10.2013

Is the Sun always straight up at noontime? No. For example, the Sun never appears directly overhead from locations well north or south of the Earth's equator. Conversely, there is always a place on Earth where the Sun will appear at zenith at noon -- for example on the equator during an equinox.

A Prominent Solar Prominence from SOHO
30.03.2004

One of the most spectacular solar sights is a prominence. A solar prominence is a cloud of solar gas held above the Sun's surface by the Sun's magnetic field. Last month, NASA's Sun-orbiting SOHO spacecraft imaged an impressively large prominence hovering over the surface, pictured above.

3I/ATLAS Flyby
26.12.2025

Attention grabbing interstellar visitor 3I/ATLAS made its not-so-close flyby of our fair planet on December 19 at a distance of 1.8 astronomical units. That's about 900 light-seconds. This deep exposure captures the comet...