Planetary Alignment over Italy
19.12.2021

It is not a coincidence that planets line up. That's because all of the planets orbit the Sun in (nearly) a single sheet called the plane of the ecliptic. When viewed from inside that plane -- as Earth dwellers are likely to do -- the planets all appear confined to a single band.

APOD: 2023 March 27 Б Aurora Over Arctic Henge
27.03.2023

Reports of powerful solar flares started a seven-hour quest north to capture modern monuments against an aurora-filled sky. The peaks of iconic Arctic Henge in Raufarhцfn in northern Iceland were already aligned with the stars: some are lined up toward the exact north from one side and toward exact south from the other.

Southwest Mercury
13.02.2000

The planet Mercury resembles a moon. Mercury's old surface is heavily cratered like many moons. Mercury is larger than most moons but smaller than Jupiter's moon Ganymede and Saturn's moon Titan. Mercury is much denser and more massive than any moon, though, because it is made mostly of iron.

A Triangular Shadow of a Large Volcano
5.07.2011

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.

A Blue Blood Moon
3.10.2015

This sharp telescopic snapshot caught late September's Harvest Moon completely immersed in Earth's dark umbral shadow, at the beginning of a total lunar eclipse. It was the final eclipse in a tetrad, a string of four consecutive total lunar eclipses.

South Celestial Rocket Launch
28.02.2020

At sunset on December 6 a Rocket Lab Electron rocket was launched from a rotating planet. With multiple small satellites on board it departed on a mission to low Earth orbit dubbed Running Out of Fingers from Mahia Peninsula on New Zealand's north island.

Three Planets and a Comet
23.12.2021

Are you still looking for that perfect holiday gift for an astronomer? If your night sky is dark and horizon clear enough, the Solar System may have done your shopping for you. Send them outside after sunset to see three planets and a comet.

September Sunrise Shadows
24.09.2022

The defining astronomical moment for this September's equinox was on Friday, September 23, 2022 at 01:03 UTC, when the Sun crossed the celestial equator moving south in its yearly journey through planet Earth's sky.

APOD: 2026 May 8 Б Comet R3 PanSTARRS Before Rigel
8.05.2026

Which way is Comet R3 PanSTARRS going? Not towards the star at the top of the image, because that is Rigel, which, being far in the background, is unrelated to the comet. Not through...

A Triangular Shadow of a Large Volcano
9.06.2019

Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes.