Highlights of the Winter Sky
11.12.2017

What's up in the sky this winter? The featured graphic gives a few highlights for Earth's northern hemisphere. Viewed as a clock face centered at the bottom, early winter sky events fan out toward the left, while late winter events are projected toward the right.

APOD: 2023 December 4 Б Plane Crossing Crescent Moon
3.12.2023

No, the Moon is not a bow, and no, it did not shoot out a plane like an arrow. What is pictured is a chance superposition. The plane's contrail would normally appear white...

Hale-Bopp Brightest Comet This Decade
12.03.1997

The Great Comet of 1997 is now brighter than the Great Comet of 1996 ever was. In fact, it is brighter than almost every star in the sky. Yet Comet Hale-Bopp is still about two weeks away from maximum light.

Mercury on the Horizon
19.03.2000

Have you ever seen the planet Mercury? Because Mercury orbits so close to the Sun, it is never seen far from the Sun, and so is only visible near sunrise or sunset. If trailing the Sun, Mercury will be visible for several minutes before it follows the Sun behind the Earth.

Planets Align Over Australian Radio Telescope Array
9.03.2008

Last week, Mercury, Venus, and the Moon all appeared close together in Earth's sky. This picturesque conjunction was caught on camera behind elements of the Australia Telescope Compact Array (ATCA) near the town of Narrabri in rural New South Wales.

Shuttle Plume Shadow Points to the Moon
27.11.2011

Why would the shadow of a space shuttle launch plume point toward the Moon? In early 2001 during a launch of Atlantis, the Sun, Earth, Moon, and rocket were all properly aligned for this photogenic coincidence.

A Solstice Sunset Self Portrait
21.06.2013

Today, the solstice is at 05:04 Universal Time, the Sun reaching the northernmost declination in its yearly journey through planet Earth's sky. A June solstice marks the astronomical beginning of summer in the northern hemisphere and winter in the south.

APOD: 2025 May 5 Б Planet Lines Across Water
4.05.2025

WhatБs causing those lines? Objects in the sky sometimes appear reflected as lines across water Б but why? If the waterБs surface is smooth, then reflected objects would appear similarly -- as spots.

APOD: 2025 September 6 Б Sardinia Sunset
5.09.2025

When the sun sets on September 7, the Full Moon will rise. And on that date denizens around much of our fair planet, including parts of Antarctica, Australia, Asia, Europe, and Africa can witness a total lunar eclipse, with the Moon completely immersed in Earth's shadow.

Comet Ikeya Zhang over Tenerife
25.03.2002

Comet Ikeya-Zhang has become bright enough to stand out in the night sky. Discovered February 1, the comet has now just rounded the Sun and has likely attained its peak brightness. The comet appears...