APOD: 2024 February 28 Б Shades of Night
27.02.2024

How does the sky turn dark at night? In stages, and with different characteristic colors rising from the horizon. The featured image shows, left to right, increasingly late twilight times after sunset in 20 different vertical bands. The picture was taken last month in Syracuse, Sicily, Italy, in the direction opposite the Sun.

Eclipsed Moon in the Milky Way
17.06.2011

On June 15, the totally eclipsed Moon was very dark, with the Moon itself positioned on the sky toward the center of our Milky Way Galaxy. This simple panorama captures totality from northern Iran in 8 consecutive exposures each 40 seconds long.

The Horsehead Nebula
15.12.2015

The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula in the center of the above photograph. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright red emission nebula.

Spiral Galaxies Spinning Super Fast
4.11.2019

Why are these galaxies spinning so fast? If you estimated each spiral's mass by how much light it emits, their fast rotations should break them apart. The leading hypothesis as to why these galaxies don't break apart is dark matter -- mass so dark we can't see it.

Sonified: The Matter of the Bullet Cluster
15.12.2020

What's the matter with the Bullet Cluster? This massive cluster of galaxies (1E 0657-558) creates gravitational lens distortions of background galaxies in a way that has been interpreted as strong evidence for the leading theory: that dark matter exists within.

A Total Eclipse Over Africa
11.07.2001

What's that dark spot on the Sun? It's the Moon. Last month, on June 21, a total solar eclipse was visible in parts of Africa. In one of the most spectacular records of this eclipse, Cees Bassa captured the setting Sun being eclipsed in a series of multiple exposures from Malambanyama, Zambia.

New York at Night
18.11.1995

This tantalizingly clear photo of New York City at night was taken by the astronauts during the Space Radar Laboratory mission of the Space Shuttle Endeavor in March of 1990. In this view, oriented with East up and North to the left, a dense constellation of lights defines the major metropolitan areas.

In the Center of the Omega Nebula
1.05.2002

In the depths of the dark clouds of dust and molecular gas known as the Omega Nebula, stars continue to form. The above image from the Hubble Space Telescope's newly installed Advanced Camera for Surveys shows unprecedented detail in the famous star-forming region.

Molecular Cloud Barnard 68
1.02.2003

Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gas absorb practically all the visible light emitted from background stars.

X-Ray Moon
4.10.2003

This x-ray image of the Moon was made by the orbiting ROSAT (Röntgensatellit) Observatory in 1990. In this digital picture, pixel brightness corresponds to x-ray intensity. Consider the image in three parts: the bright hemisphere of the x-ray moon, the darker half of the moon, and the x-ray sky background.