Apollo s Analemma
22.09.2013

Today, the Sun crosses the celestial equator heading south at 20:44 Universal Time. An equinox (equal night), this astronomical event marks the first day of autumn in the northern hemisphere and spring in the south.

Sunspot Loops in Ultraviolet
10.10.2004

It was a quiet day on the Sun. The above image shows, however, that even during off days the Sun's surface is a busy place. Shown in ultraviolet light, the relatively cool dark regions have temperatures of thousands of degrees Celsius.

Sunspot Loops in Ultraviolet
11.06.2006

It was a quiet day on the Sun. The above image shows, however, that even during off days the Sun's surface is a busy place. Shown in ultraviolet light, the relatively cool dark regions have temperatures of thousands of degrees Celsius.

Sunset on a Golden Sea
28.04.2010

On April 17, the sky was clear and the Sun's colour was spectacular as night approached. This striking telescopic view even captures the Sun's swollen and distorted shape from the southern coast of the UK.

APOD: 2024 September 1 Б The Moon Dressed Like Saturn
1.09.2024

Why does Saturn appear so big? It doesn't -- what is pictured are foreground clouds on Earth crossing in front of the Moon. The Moon shows a slight crescent phase with most of its surface visible by reflected Earthlight, known as Da Vinci glow.

APOD: 2025 March 30 Б A Partial Solar Eclipse over Iceland
30.03.2025

What if the Sun and Moon rose together? That happened yesterday over some northern parts of planet Earth as a partial solar eclipse occurred shortly after sunrise. Regions that experienced the Moon blocking part of the Sun included northeastern parts of North America and northwestern parts of Europe, Asia, and Africa.

Time Lapse: A Total Solar Eclipse
10.12.2012

Have you ever experienced a total eclipse of the Sun? The above time-lapse movie depicts such an eclipse in dramatic detail as visible from Australia last month. As the video begins, a slight dimming of the Sun and the surrounding Earth is barely perceptible.

AR 9169: A Large Sunspot
25.09.2000

One of the largest sunspots in recent years is now crossing our Sun. Dominating active region AR 9169, the sunspot is the large dark complex visible below (west) and right of center in the above photograph of our Sun taken last Thursday.

A Powerful Solar Flare
29.10.2003

Yesterday, our Sun produced one of the most powerful solar flares in recorded history. Seen across the electromagnetic spectrum, the Sun briefly became over 100 times brighter in X-rays than normal. Over the next few days, as energetic particles emitted from these regions strike the Earth, satellite communications might be affected and auroras might develop.

APOD: 2025 October 6 Б The Changing Ion Tail of Comet Lemmon
6.10.2025

How does a comet tail change? It depends on the comet. The ion tail of Comet C/2025 A6 (Lemmon) has been changing markedly, as detailed in the featured image sequenced over six days between September 25 and October 4 (left to right) from Texas, USA.