Some 60 million light-years away in the southerly constellation Corvus, two large galaxies are colliding. Stars in the two galaxies, cataloged as NGC 4038 and NGC 4039, very rarely collide in the course of the ponderous cataclysm that lasts for hundreds of millions of years. But the galaxies’ large clouds of molecular gas and dust often do, triggering furious episodes of star formation near the center of the cosmic wreckage. Spanning over 500 thousand light-years, this stunning view also reveals new star clusters and matter flung far from the scene of the accident by gravitational tidal forces. The remarkable mosaicked image was constructed using data from the ground-based Subaru telescope to bring out large-scale and faint tidal streams, and Hubble Space Telescope data of extreme detail in the bright cores. The suggestive visual appearance of the extended arcing structures gives the galaxy pair its popular name – The Antennae.
Earth’s annual Lyrid meteor shower peaked before dawn on April 22nd, as our fair planet plowed through dust from the tail of long-period comet Thatcher. Seen from the high, dark, and dry Atacama desert a waning crescent Moon and brilliant Venus join Lyrid meteor streaks in this composited view. Captured over 5 hours on the night of April 21/22, the meteors stream away from the shower’s radiant, a point not very far on the sky from Vega, alpha star of the constellation Lyra. The radiant effect is due to perspective as the parallel meteor tracks appear to converge in the distance. In the foreground are domes of the Las Campanas Observatory housing (left to right) the 2.5 meter du Pont Telescope and the 1.3 meter Optical Gravitational Lensing Experiment (OGLE) telescope.
Mt. Etna has been erupting for hundreds of thousands of years. Located in Sicily, Italy, the volcano produces lava fountains over one kilometer high. Mt. Etna is not only one of the most active volcanoes on Earth, it is one of the largest, measuring over 50 kilometers at its base and rising nearly 3 kilometers high. Pictured in mid-March, a spectacular lava plume erupts upwards, dangerous molten volcanic bombs fly off to the sides, while hot lava flows down the volcano’s exterior. The Earth’s rotation is discernable on this carefully time, moon-lit, long duration image as star trails.
A day before its closest approach, asteroid 2014 JO25 was imaged by radar with the 70-meter antenna of NASA’s Goldstone Deep Space Communications Complex in California. This grid of 30 radar images, top left to lower right, reveals the two-lobed shape of the asteroid that rotates about once every five hours. Its largest lobe is about 610 meters across. On the list of Potentially Hazardous Asteroids, this space rock made its close approach to our fair planet on April 19, flying safely past at a distance of 1.8 million kilometers. That’s over four times the distance from the Earth to the Moon. The asteroid was a faint and fast moving speck visible in backyard telescopes. Asteroid 2014 JO25 was discovered in May 2014 by the Catalina Sky Survey, a project of NASA’s Near-Earth Objects Observations Program in collaboration with the University of Arizona.
On April 10, a Full Moon and Jupiter shared this telephoto field of view. Both were near opposition, opposite the Sun in Earth’s night sky. Captured when a passing cloud bank dimmmed the bright moonlight slightly, the single exposure reveals the familiar face of our fair planet’s own large natural satellite, along with a line up of the ruling gas giant’s four Galilean moons. Labeled top to bottom, the tiny pinpricks of light above bright Jupiter are Callisto, Europa, Ganymede, and Io. Closer and brighter, our own natural satellite appears to loom large. But Callisto, Ganymede, and Io are physically larger than Earth’s Moon, while water world Europa is only slightly smaller. In fact, of the Solar System’s six largest planetary satellites, only Saturn’s moon Titan is missing from the scene.
This was supposed to be a shot of trees in front of a setting Sun. Sometimes, though, the unexpected can be photogenic. During some planning shots, a man walking his dog unexpected crossed the ridge. The result was so striking that, after cropping, it became the main shot. The reason the Sun appears so large is that the image was taken from about a kilometer away through a telephoto lens. Scattering of blue light by the Earth’s atmosphere makes the bottom of the Sun appear slightly more red that the top. Also, if you look closely at the Sun, just above the man’s head, a large group of sunspots is visible. The image was taken just last week in Bad Mergentheim, Germany.
Comet Hale-Bopp, the Great Comet of 1997, became much brighter than any surrounding stars. It was seen even over bright city lights. Away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains surrounding Cortina d’Ampezzo, Italy. Comet Hale-Bopp‘s blue ion tail, consisting of ions from the comet’s nucleus, is pushed out by the solar wind. The white dust tail is composed of larger particles of dust from the nucleus driven by the pressure of sunlight, that orbit behind the comet. Comet Hale-Bopp (C/1995 O1) remained visible to the unaided eye for 18 months — longer than any other comet in recorded history. This year marks the 20th anniversary of Comet Hale-Bopp’s last trip to the inner Solar System. The large comet is next expected to return around the year 4385.