Artificial Night Sky Brightness
27.08.2001

Where have all the dim stars gone? From many places on the Earth including major cities, the night sky has been reduced from a fascinating display of hundreds of stars to a diffuse glow through which only a handful of stars are visible.

APOD: 2025 December 15 Б Gemini Meteors over Snow Capped Mountains
15.12.2025

Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Gemini. That is why the major meteor shower in December is known as the Geminids -- because shower meteors all appear to come from a radiant toward Gemini.

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.

Perseid Meteors over Mount Shasta
8.08.2016

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 meteor shower that peaks later this week is known as the Perseids -- the meteors all appear to came from a radiant toward Perseus.

Galaxies Of The Virgo Cluster
26.01.2001

Well over a thousand galaxies are known members of the Virgo Cluster, the closest large cluster of galaxies to our own local group. The galaxy cluster is difficult to see all at once because it covers such a large area on the sky.

Meteors, Comet, and Big Dipper over La Palma
23.04.2019

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.

Geminids from Gemini
16.11.2021

Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Gemini. That is why the major meteor shower in December is known as the Geminids -- because shower meteors all appear to come from a radiant toward Gemini.

Lyrid Meteors from the Constellation Lyra
12.05.2020

Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Small Harp (Lyra). That is why the famous meteor shower that peaks every April is known as the Lyrids -- the meteors all appear to came from a radiant toward Lyra.

Virgo Cluster Galaxies
4.08.2015

Well over a thousand galaxies are known members of the Virgo Cluster, the closest large cluster of galaxies to our own local group. In fact, the galaxy cluster is difficult to appreciate all at once because it covers such a large area on the sky.

Virgo Cluster Galaxies
22.04.2011

Well over a thousand galaxies are known members of the Virgo Cluster, the closest large cluster of galaxies to our own local group. In fact, the galaxy cluster is difficult to appreciate all at once because it covers such a large area on the sky.