A Fading Moonset Over Hong Kong
14.12.2009

Do stars appear dimmer when nearer the horizon? Yes -- atmospheric air absorbs and reradiates light, so that the greater the airmass through which one peers, the fainter an object will appear. Pictured above in a multi-frame image, stars, the planet Jupiter, and even the Moon show the horizon-dimming effects of Earth's nearly-transparent atmosphere.

A Beautiful Trifid
19.10.2017

The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane...

M31 versus M33
25.09.2015

Separated by about 14 degrees (28 Full Moons) in planet Earth's sky, spiral galaxies M31 at left, and M33 are both large members of the Local Group, along with our own Milky Way galaxy.

APOD: 2025 July 9 Б A Beautiful Trifid
8.07.2025

The beautiful Trifid Nebula is a cosmic study in contrasts. Also known as M20, it lies about 5,000 light-years away toward the nebula rich constellation Sagittarius. A star forming region in the plane...

APOD: 2025 March 4 Б A Quadruple Alignment over Italy
3.03.2025

Why does this Moon look so unusual? A key reason is its vivid red color. The color is caused by the deflection of blue light by Earth's atmosphere -- the same reason that the daytime sky appears blue. The Moon also appears unusually distorted.

Jupiter s Triple Shadow Transit
2.11.2013

This webcam and telescope image of banded gas giant Jupiter shows the transit of three shadows cast by Jupiter's moons in progress, captured in Belgian skies on October 12 at 0528 UT. Such a three shadow transit is a relatively rare event, even for a large planet with many moons.

Apollo 14 Heads for Home
4.02.2021

Fifty years ago this Sunday (February 7, 1971), the crew of Apollo 14 left lunar orbit and headed for home. They watched this Earthrise from their command module Kittyhawk. With Earth's sunlit crescent just peeking over the lunar horizon, the cratered terrain in the foreground is along the lunar farside.

Happy Birthday Jules Verne
5.02.1998

Sunday marks the 170th anniversary of the birth of Jules Verne (born in Nantes, France on the 8th of February, 1828). Inspired by a lifelong fascination with machines, Verne wrote visionary works about "Extraordinary...

A Blue Moon Halo over Antarctica
10.08.2015

Have you ever seen a halo around the Moon? Such 22 degree rings around the Moon -- caused by ice crystals falling in the Earth's atmosphere -- are somewhat rare. OK, but have you ever seen a blue moon?

Two Views, Two Crescents
10.11.2010

Venus rose in a glowing dawn sky on November 5th, just before the Sun. For early morning risers, its brilliant crescent phase was best appreciated with binoculars or a small telescope. On that...