Crescent Venus and Moon
16.05.2010

There's something behind these clouds. Those faint graceful arcs, upon inspection, are actually far, far in the distance. They are the Earth's Moon and the planet Venus. Both the Moon and Venus are bright enough to be seen during the day, and both are quite capable of showing a crescent phase.

Roll Cloud Over Wisconsin
31.08.2011

What kind of cloud is this? A type of arcus cloud called a roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud.

The Summer Triangle over the Great Wall
3.07.2017

Have you ever seen the Summer Triangle? The bright stars Vega, Deneb, and Altair form a large triangle on the sky that can be seen rising in the northern spring during the morning, and rising in the northern fall during the evening.

Leaving Earth
9.08.2022

What it would look like to leave planet Earth? Such an event was recorded visually in great detail by the MESSENGER spacecraft as it swung back past the Earth in 2005 on its way in toward the planet Mercury. Earth can be seen rotating in this time-lapse video, as it recedes into the distance.

3D Bennu
11.03.2023

Put on your red/blue glasses and float next to asteroid 101955 Bennu. Shaped like a spinning toy top with boulders littering its rough surface, the tiny Solar System world is about one Empire State Building (less than 500 meters) across.

IC 4628: The Prawn Nebula
7.09.2012

South of Antares, in the tail of the nebula-rich constellation Scorpius, lies emission nebula IC 4628. Nearby hot, massive stars, millions of years young, radiate the nebula with invisible ultraviolet light, stripping electrons from atoms. The electrons eventually recombine with the atoms to produce the visible nebular glow, dominated by the red emission of hydrogen.

A Roll Cloud Over Uruguay
2.06.2013

What kind of cloud is this? A roll cloud. These rare long clouds may form near advancing cold fronts. In particular, a downdraft from an advancing storm front can cause moist warm air to rise, cool below its dew point, and so form a cloud.

Aphelion Sunrise
5.07.2017

On July 3rd, planet Earth reached aphelion, the farthest point in its elliptical orbit around the Sun. Each year, this day of the most distant Sun happens to occur during winter in the southern hemisphere.

M101: The Pinwheel Galaxy
14.04.2009

Why do many galaxies appear as spirals? A striking example is M101, shown above, whose relatively close distance of about 27 million light years allow it to be studied in some detail. Recent evidence...

Lynds Dark Nebula 183
21.10.2017

Beverly Lynds Dark Nebula 183 lies a mere 325 light-years away, drifting high above the plane of our Milky Way Galaxy. Obscuring the starlight behind it when viewed at optical wavelengths, the dark, dusty molecular cloud itself seems starless.