APOD: 2024 July 14 Б Meteor Misses Galaxy
14.07.2024

The galaxy was never in danger. For one thing, the Triangulum galaxy (M33), pictured, is much bigger than the tiny grain of rock at the head of the meteor. For another, the galaxy is much farther away -- in this instance 3 million light years as opposed to only about 0.0003 light seconds.

APOD: 2026 February 10 Б In Green Company: Aurora over Norway
10.02.2026

Raise your arms if you see an aurora. With those instructions, two nights went by with, well, clouds -- mostly. On the third night of returning to same peaks, though, the sky not only cleared up but lit up with a spectacular auroral display.

APOD: 2020 August 24 Б Crescent Moon HDR
24.08.2020

How come the crescent Moon doesn't look like this? For one reason, because your eyes can't simultaneously discern bright and dark regions like this. Called earthshine or the da Vinci glow...

APOD: 2023 February 28 Б Crescent Moon Beyond Greek Temple
28.02.2023

Why is a thin crescent moon never seen far from a horizon? Because the only geometry that gives a thin crescent lunar phase occurs when the Moon appears close to the Sun in the sky.

APOD: 2024 September 22 Б Chicagohenge: Equinox in an Aligned City
22.09.2024

Chicago, in a way, is like a modern Stonehenge. The way is east to west, and the time is today. Today, and every equinox, the Sun will set exactly to the west, everywhere on Earth.

APOD: 2023 November 29 Б A Landspout Tornado over Kansas
29.11.2023

Could there be a tornado inside another tornado? In general, no. OK, but could there be a tornado inside a wider dust devil? No again, for one reason because tornados comes down from the sky, but dust devils rise up from the ground.

APOD is Five Years Old Today
16.06.2000

Welcome to the sixth year of Astronomy Picture of the Day (APOD)! Above are the industrious Robert Nemiroff (left) and persistent Jerry Bonnell (right), still engaged in creating the APOD web pages. As suggested...

APOD: 2024 May 30 Б A Lunar Corona over Paris
30.05.2024

Why does a cloudy moon sometimes appear colorful? The effect, called a lunar corona, is created by the quantum mechanical diffraction of light around individual, similarly-sized water droplets in an intervening but mostly-transparent cloud. Since light of different colors has different wavelengths, each color diffracts differently.

APOD: 2024 October 14 Б Comet Tsuchinshan ATLAS Over the Lincoln Memorial
14.10.2024

Go outside at sunset tonight and see a comet! C/2023 A3 (TsuchinshanБATLAS) has become visible in the early evening sky in northern locations to the unaided eye. To see the comet, look west through a sky with a low horizon.

APOD: 2025 July 11 Б The Veins of Heaven
11.07.2025

Transfusing sunlight as the sky grew darker, this exceptional display of noctilucent clouds was captured on July 10, reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden. From the edge of space...