Category: Image of the Day

Moon Pairs and the Synodic Month

Observe the Moon each night and its visible sunlit portion will gradually change. In phases progressing from New Moon to Full Moon to New Moon again, a lunar cycle or synodic month is completed in about 29.5 days. They look...

/ September 26, 2020

Moon over Andromeda

The Great Spiral Galaxy in Andromeda (also known as M31), a mere 2.5 million light-years distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but...

/ September 25, 2020

Enceladus in Infrared

One of our Solar System’s most tantalizing worlds, icy Saturnian moon Enceladus appears in these detailed hemisphere views from the Cassini spacecraft. In false color, the five panels present 13 years of infrared image data from Cassini’s Visual and Infrared...

/ September 24, 2020

ISS Transits Mars

Yes, but have you ever seen the space station do this? If you know when and where to look, watching the bright International Space Station (ISS) drift across your night sky is a fascinating sight — but not very unusual....

/ September 23, 2020

Equinox in the Sky

Does the Sun set in the same direction every day? No, the direction of sunset depends on the time of the year. Although the Sun always sets approximately toward the west, on an equinox like today the Sun sets directly...

/ September 22, 2020

Omega Sunrise

Capturing this sunrise required both luck and timing. First and foremost, precise timing was needed to capture a sailboat crossing right in front of a rising Sun. Additionally, by a lucky coincidence, the background Sun itself appears unusual — it...

/ September 21, 2020

Breaking Distant Light

In the distant universe, time appears to run slowly. Since time-dilated light appears shifted toward the red end of the spectrum (redshifted), astronomers are able to use cosmological time-slowing to help measure vast distances in the universe. Featured, the light...

/ September 20, 2020

Orion in Depth

Orion is a familiar constellation. The apparent positions of its stars in two dimensions create a well-known pattern on the bowl of planet Earth’s night sky. Orion may not look quite so familiar in this 3D view though. The illustration...

/ September 19, 2020

Arp 78: Peculiar Galaxy in Aries

(xxxedit and linkxxx) Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries, some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy. Also known as NGC 772, the island...

/ September 18, 2020

Solar Cycle 25 Begins

The general trend of monthly sunspot data now confirms that the minimum of the approximately 11 year cycle of solar activity occurred in December 2019, marking the start of Solar Cycle 25. That quiet Sun, at minimum activity, appears on...

/ September 17, 2020