Cherenkov Telescope at Sunset
17.10.2018

On October 10, a new telescope reflected the light of the setting Sun. With dark horizon above and sunset colors below, its segmented mirror inverts an image of the beautiful evening sky in this snapshot from the Roque del Los Muchachos Observatory on the Canary Island of La Palma.

The Case of the Missing Supernova
13.04.1999

Would you notice a second Moon in the sky? About 700 years ago, light from a tremendous explosion reached Earth that should have appeared almost as bright as a full Moon. The bright spot should have lasted for weeks, yet no notation of such an occurrence has been found in historical records.

Swift RocketCam
23.12.2004

A forward-facing RocketCam (TM) mounted inside the payload fairing of a Delta II rocket captured these dramatic video frames on November 20th -- as the Swift satellite observatory journeyed to an orbit 600 kilometers above planet Earth. Some frames were interpolated to correct for transmission problems.

GRB 060218: A Mysterious Transient
26.02.2006

What is it? Something is happening in a small portion of the sky toward the constellation of Aries and telescopes around the globe are tracking an unusual transient there as it changes day by day. No one is sure what it will do next.

Fermi Science Finals
22.07.2018

The Fermi Science Playoffs celebrate 10 years of the Fermi Gamma-ray Space Telescope's exploration of the high-energy universe. Surviving all early rounds of voting, these two finalists in the competion square off at last.

APOD: 2020 August 31 Б SS 433: Binary Star Micro Quasar
30.08.2020

SS 433 is one of the most exotic star systems known. Its unremarkable name stems from its inclusion in a catalog of Milky Way stars which emit radiation characteristic of atomic hydrogen. Its remarkable behavior stems from a compact object, a black hole or neutron star, which has produced an accretion disk with jets.

Compton Returns
6.03.2001

On 2000 June 4, the 17-ton Compton Gamma-Ray Observatory returned to Earth after 9 years in orbit -- ending its remarkable voyage of discovery. The massive, bus-sized spacecraft carried an unprecedented array of gamma-ray detectors which explored the bizarre, high-energy universe of solar flares, black holes, pulsars, supernovae, active galaxies, and gamma-ray bursts.

Boosting Compton
6.06.1997

Even great observatories need a boost from time to time -- including the orbiting Compton Gamma-Ray Observatory. Sparkling reflections and the bright limb of the Earth are visible in this 1991 window view of Compton's release into orbit by the crew of the Space Shuttle Atlantis.

A Dark Pulsar in CTA 1
21.10.2008

Where's the pulsar? Previously, the nebula CTA 1 showed an expanding supernova remnant, a jet, and a point source expected to be a pulsar -- a rotating neutron star producing pulses at radio energies. But no radio pulses were detected.

Fermi Epicyles: The Vela Pulsar s Path
4.05.2012

Exploring the cosmos at extreme energies, the Fermi Gamma-ray Space Telescope orbits planet Earth every 95 minutes. By design, it rocks to the north and then to the south on alternate orbits in order to survey the sky with its Large Area Telescope (LAT).