Get out your red/blue glasses and float next to Helene, small, icy moon of Saturn. Appropriately named, Helene is one of four known Trojan moons, so called because it orbits at a Lagrange point. A Lagrange point is a gravitationally stable position near two massive bodies, in this case Saturn and larger moon Dione. In fact, irregularly shaped ( about 36 by 32 by 30 kilometers) Helene orbits at Dione’s leading Lagrange point while brotherly ice moon Polydeuces follows at Dione’s trailing Lagrange point. The sharp stereo anaglyph was constructed from two Cassini images captured during a close flyby in 2011. It shows part of the Saturn-facing hemisphere of Helene mottled with craters and gully-like features.
Why does the shadow of this volcano look like a triangle? The Mount Teide volcano itself does not have the strictly pyramidal shape that its geometric shadow might suggest. The triangle shadow phenomena is not unique to the Mt. Teide, though, and is commonly seen from the tops of other large mountains and volcanoes. A key reason for the strange dark shape is that the observer is looking down the long corridor of a sunset (or sunrise) shadow that extends to the horizon. Even if the huge volcano were a perfect cube and the resulting shadow were a long rectangular box, that box would appear to taper off at its top as its shadow extended far into the distance, just as parallel train tracks do. The featured spectacular image shows Pico Viejo crater in the foreground, located on Tenerife in the Canary Islands of Spain. The nearly full moon is seen nearby shortly after its total lunar eclipse.
At the end of last year’s northern summer, after its dazzling opposition, Mars still shone brightly in the night. The celestial beacon easily attracted the attention of these two night skygazers who stood still for just a while, but long enough to be captured in the sea and night skyscape from Big Sur, planet Earth. Its central bulge near the southwestern horizon, the Milky Way runs through the scene too, while the long exposure also reveals a faint blue bioluminescence blooming in the waves along Pfeiffer Beach. Now much fainter, Mars can be spotted near the western horizon after sunset, but this month Jupiter is near its closest and brightest, reaching its own opposition on June 10. Night skygazers can spot brilliant Jupiter over southern horizons, glaring next to the stars toward the central Milky Way.
Now posing against our galaxy’s rich starfields and nebulae, brilliant planet Jupiter shines in the night sky. Its almost overwhelming glow is near the top of the frame in this colorful telephoto portrait of the central Milky Way. Spanning about 20 degrees on the sky, the scene includes the silhouette of LDN 1773 against the starlight, also know by the popular moniker the Pipe Nebula for its apparent outline of stem and bowl. The Pipe Nebula is part of the galaxy’s Ophiuchus dark cloud complex. Located at a distance of about 450 light-years, dense cores of gas and dust within are collapsing to form stars. Approaching its opposition, opposite the Sun in the sky on June 12, Jupiter is only about 36 light-minutes from planet Earth. Fans of dark markings on the sky can probably spot the Snake Nebula below and left of Jupiter’s glare.
A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across. That’s about the size of our own Milky Way Galaxy. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core in this sharp telescopic portrait. Its sweeping blue spiral arms are streaked with cosmic dust lanes and dotted with pink star forming regions. A dominant member of a known galaxy group, M63 has faint, extended features that are likely star streams from tidally disrupted satellite galaxies. M63 shines across the electromagnetic spectrum and is thought to have undergone bursts of intense star formation.
The constellation of Orion is much more than three stars in a row. It is a direction in space that is rich with impressive nebulas. To better appreciate this well-known swath of sky, a new long exposure image was taken over several clear nights in January, February and March. After 23 hours of camera time and untold hours of image processing, the featured collage in the light of hydrogen, oxygen, and sulfur was produced spanning over 40 times the angular diameter of the Moon. Of the many interesting details that have become visible, one that particularly draws the eye is Barnard’s Loop, the bright red orange arc just to the right of the image center. The Rosette Nebula is not the giant orange nebula just to the left of the image center — that is larger but lesser known nebula known as the Meissa Ring. The Rosette Nebula is visible, though: it is the bright orange, blue and white nebula near the image bottom. The bright orange star just left of the frame center is Betelgeuse, while the bright blue star on the upper right is Rigel. About those famous three stars that cross the belt of Orion the Hunter — in this busy frame they can be hard to locate, but a discerning eye will find them just to the right of the image center.
When did these big galaxies first begin to dance? Really only four of the five of Stephan’s Quintet are locked in a cosmic tango of repeated close encounters taking place some 300 million light-years away. The odd galaxy out is easy to spot in this recently reprocessed image by the Hubble Space Telescope — the interacting galaxies, NGC 7319, 7318B, 7318A, and 7317 (left to right), have a more dominant yellowish cast. They also tend to have distorted loops and tails, grown under the influence of disruptive gravitational tides. The mostly bluish galaxy, large NGC 7320 on the lower left, is in the foreground at about 40 million light-years distant, and so is not part of the interacting group. Data and modeling indicate that NGC 7318B is a relatively new intruder. A recently-discovered halo of old red stars surrounding Stephan’s Quintet indicate that at least some of these galaxies started tangling over a billion years. Stephan’s Quintet is visible with a moderate sized-telescope toward the constellation of Winged Horse (Pegasus).