MESSENGER at Mercury
31.03.2011

On March 17, the MESSENGER spacecraft became the first to orbit Mercury, the solar system's innermost planet. This is its first processed color image since entering Mercury orbit. Larger, denser, and with almost twice the surface gravity of Earth's moon, Mercury still looks moon-like at first glance.

A Bubbling Galaxy Center
12.06.2000

What's happening in the center of this galaxy? Close inspection of the center of NGC 4438, as visible in this recently released representative-color image by the Hubble Space Telescope, reveals an unusual bubble of hot gas, colored in red.

Von Braun's Wheel
2.03.1996

Orbiting 1,075 miles above the Earth, a 250 foot wide, inflated, reinforced nylon "wheel" was conceived in the early 1950s to function as a navigational aid, meteorological station, military platform, and way station for space exploration by rocket pioneer Wernher von Braun.

Ring Around the Cluster
4.01.1999

It is difficult to hide a galaxy behind a cluster of galaxies. The closer cluster's gravity will act like a huge lens, pulling images of the distant galaxy around the sides and greatly distorting them. This is just the case observed in the above recently released image from the VLT.

A Network of Microlensing Caustics
24.08.1999

A virtual sky map like this would be of interest to astronomers studying gravitational microlensing. In microlensing, the gravity of stars near the line of sight can act to magnify the light of background objects such as distant stars, or quasars. Nowhere is this magnification greater than near a gravitational lensing caustic.

Galaxies in the River
11.12.2025

Large galaxies grow by eating small ones. Even our own galaxy engages in a sort of galactic cannibalism, absorbing small galaxies that are too close and are captured by the Milky Way's gravity.

Galaxies in the River
17.07.2010

Large galaxies grow by eating small ones. Even our own galaxy practices galactic cannibalism, absorbing small galaxies that get too close and are captured by the Milky Way's gravity. In fact, the practice...

Unexpected Trajectory Interstellar Asteroid Oumuamua
20.11.2018

Why is 'Oumuamua differing from its expected trajectory? Last year, 1I/2017 U1 'Oumuamua became the first known asteroid from interstellar space to pass through our Solar System. Just over a year ago, this tumbling interstellar rock even passed rather close to the Earth.

Philae Attempts Comet Nucleus Landing
11.11.2014

Today humanity will make its first attempt to land a probe on the nucleus of a comet. As the day progresses, the Philae (fee-LAY) lander will separate from the Rosetta spacecraft and head down...

Daphnis the Wavemaker
21.01.2017

Plunging close to the outer edges of Saturn's rings, on January 16 the Cassini spacecraft captured this closest yet view of Daphnis. About 8 kilometers across and orbiting within the bright ring system's Keeler gap, the small moon is making waves.