Zeta Oph: Runaway Star
8.04.2017

Like a ship plowing through cosmic seas, runaway star Zeta Ophiuchi produces the arcing interstellar bow wave or bow shock seen in this stunning infrared portrait. In the false-color view, bluish Zeta...

A Force from Empty Space: The Casimir Effect
3.01.2010

This tiny ball provides evidence that the universe will expand forever. Measuring slightly over one tenth of a millimeter, the ball moves toward a smooth plate in response to energy fluctuations in the vacuum of empty space.

A Fox Fur, a Unicorn, and a Christmas Tree
10.04.2012

What do the following things have in common: a cone, the fur of a fox, and a Christmas tree? Answer: they all occur in the constellation of the unicorn (Monoceros). Pictured above...

The Red Rectangle Nebula from Hubble
21.05.2013

How was the unusual Red Rectangle nebula created? At the nebula's center is an aging binary star system that surely powers the nebula but does not, as yet, explain its colors. The unusual...

Mystic Mountain Monster being Destroyed
25.05.2020

Inside the head of this interstellar monster is a star that is slowly destroying it. The huge monster, actually an inanimate series of pillars of gas and dust, measures light years in length.

Total Solar Eclipse 2020
7.01.2021

Along a narrow path crossing southern South America through Chile and Argentina, the final New Moon of 2020 moved in front of the Sun on December 14 in the year's only total solar eclipse.

NGC 3314: When Galaxies Overlap
17.11.2021

Why doesn't the nearby galaxy create a gravitational lensing effect on the background galaxy? It does, but since both galaxies are so nearby, the angular shift is much smaller than the angular sizes of the galaxies themselves.

The Asymmetric Nebula Surrounding Wolf Rayet Star 18
9.11.2022

Why does the nebula around the star WR-18 shine brighter on one side? Also known as NGC 3199, this active star and its surrounding nebula lie about 12,000 light-years away toward the nautical southern constellation of Carina.

APOD: 2023 April 11 Б North Star: Polaris and Surrounding Dust
11.04.2023

Why is Polaris called the North Star? First, Polaris is the nearest bright star toward the north spin axis of the Earth. Therefore, as the Earth turns, stars appear to revolve around Polaris, but Polaris itself always stays in the same northerly direction -- making it the North Star.

NGC 7331: A Galaxy So Inclined
1.07.2004

If our own Milky Way galaxy were 50 million light-years away with its disk inclined slightly to our line of sight, it would look a lot like large spiral galaxy NGC 7331. In fact...