Perseids from Perseus
17.08.2009

Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Perseus. That is why the last week's meteor shower was known as the Perseids -- the meteors all appear to come from a radiant toward Perseus.

Meteors, Comet, and Big Dipper over La Palma
22.04.2019

Meteor showers are caused by streams of solid particles, dust size and larger, moving as a group through space. In most cases, the orbits of these meteor streams can be identified with dust expelled from a comet.

Quadrantid Meteors through Orion
19.01.2020

Why are these meteor trails nearly parallel? Because they were all shed by the same space rock and so can be traced back to the same direction on the sky: the radiant of the Quadrantid Meteor Shower.

A Waterfall and the Milky Way
31.10.2021

The dream was to capture both the waterfall and the Milky Way together. Difficulties included finding a good camera location, artificially illuminating the waterfall and the surrounding valley effectively, capturing the entire scene with...

Comet 2022 E3 ZTF
23.12.2022

Comet C/2022 E3 (ZTF) was discovered by astronomers using the wide-field survey camera at the Zwicky Transient Facility this year in early March. Since then the new long-period comet has brightened substantially and is now sweeping across the northern constellation Corona Borealis in predawn skies.

APOD: 2023 February 13 Б Comet ZTF and Mars
12.02.2023

No, Comet ZTF is not going to hit Mars. Nicknamed the Green Comet for its bright green coma, C/2022 E3 (ZTF) did, however, pass almost in front of the much-more distant planet a few days ago, very near in time to when the featured picture was taken.

APOD: 2026 April 14 Б The Long Wispy Tail of Comet R3 (PanSTARRS)
13.04.2026

Why does Comet R3 (PanSTARRS) have a wispy tail? The newest bright member of the inner Solar System, Comet C/2025 R3 (PanSTARRS) is already extending an impressive stream of glowing gas. This tail starts from an unseen central nucleus of dirty ice that is likely a few kilometers across.

Alpha Centauri: The Closest Star System
26.05.1996

The closest star system to the Sun is the Alpha Centauri system. Of the three stars in the system, the dimmest -- called Proxima Centauri -- is actually the nearest star. The bright stars Alpha Centauri...

Geostationary Satellites Beyond the Alps
11.04.2012

Why don't those stars move? Stars in the sky will typically appear to rise and set as the Earth turns. Those far to the north or south will appear to circle the pole. If you look closely at the above time-lapse movie, however, there are points of light that appear stationary.

PanSTARRS over Parkes
9.03.2013

Sweeping quickly through southern skies on March 5, Comet PanSTARRS (C/2011 L4) follows the Sun toward the western horizon in this twilight scene. In the foreground is Australia's CSIRO Parkes Radio Telescope, a 64 meter wide steerable dish that is no stranger to the space age exploration of comets.