Starlink Satellite Trails over Brazil
9.12.2019

What are those streaks over the horizon? New Starlink satellites reflecting sunlight. SpaceX launched 60 Starlink communication satellites in May and 60 more in November. These satellites and thousands more are planned by communications companies in the next few years that may make streaks like these relatively common.

APOD: 2023 January 25 Б LDN 1622: The Boogeyman Nebula
24.01.2023

To some, the dark shape looks like a mythical boogeyman. Scientifically, Lynds' Dark Nebula (LDN) 1622 appears against a faint background of glowing hydrogen gas only visible in long telescopic exposures of the region.

A Sky Full Of Hydrogen
17.12.1996

Interstellar space is filled with extremely tenuous clouds of gas which are mostly Hydrogen. The neutral hydrogen atom (HI in astronomer's shorthand) consists of 1 proton and 1 electron. The proton and electron spin like tops but can have only two orientations; spin axes parallel or anti-parallel.

Messenger Launch
14.08.2004

Streaking into the early morning sky on August 3rd, a Delta II rocket launches NASA's Messenger spacecraft on an interplanetary voyage to Mercury. Scheduled to become the first probe to orbit Mercury, Messenger will begin by looping through the inner Solar System in a series of close flybys of planet Earth and Venus.

The Radio Sky: Tuned to 408MHz
3.04.1999

Tune your radio telescope to 408MHz (408 million cycles per second) and check out the Radio Sky! You should find that frequency on your dial somewhere between US broadcast television channels 13 and 14.

A Solar Filament Erupts
20.07.2014

What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME).

A Solar Filament Erupts
15.09.2018

What's happened to our Sun? Nothing very unusual -- it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME).

Veil Nebula: Wisps of an Exploded Star
4.04.2021

Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history.

Pixels in the Sun
25.06.2021

These two panels, composed of video frames made with a safe solar telescope and hydrogen alpha filter, show remarkably sharp details on the solar disk and giant prominences along the Sun's edge on June 6 (top) and June 18.

Solstice Celebration
20.06.2004

Season's greetings! Today or tomorrow, depending on your time zone, the Sun reaches its northernmost point in planet Earth's sky marking a season change and the first solstice of the year 2004. In celebration, consider this delightfully detailed, brightly colored image of the active Sun.