One of HST’s most cited set of observations was the series of images taken in July 1994 as the dishevelled remnants of Comet Shoemaker-Levy 9 crashed into Jupiter. That event highlighted the catastrophic consequences of cosmic impacts, and sparked considerable interest in identifying earth-crossing asteroids and comets. Fifteen years later, on 19 July 2009, an Australian amateur astronomer, Anthony Wesley, noticed a strange dark ‘scar” near Jupiter’s southern pole. The feature was quickly confirmed by other astronomers, both amateur and professional, and was quickly judged as likely to be the result of another, completely unexpected, cometary impact. The SL9 impact was thought to be a once-in-a-lifetime (if not more) event; clearly, the impact rate is higher than previously suspected. At the time of the new event, HST was deeply immersed in the initial on-orbit instrument performance tests, but the science staff were able to interrupt those procedures for a few orbits to obtain images with Wide-Field Camera 3. Further observations will be obtained at a later date to track the evolution of the feature, as Jovian winds disperse the detritus through the atmosphere.
The movie on the left is a time-interpolated, evenly spaced sequence of frames showing motions in Jupiter’s atmosphere over the course of 5 days, from October 1 to October 5, 2000. The smallest features are about 500 km across.
The movie on the right is made from narrow angle blue filter images taken during 7 separate Jupiter rotations between October 1 and October 5, 2000, shows the counterclockwise atmospheric motions around the Great Red Spot. The smallest features are about 500 km across.
Credit: NASA/JPL/University of Arizona, Cosmos Studios Released: November 20, 2000
Signs of Water Found on 5 Alien Planets by Hubble Telescope
NASA’s Hubble Space Telescope has detected water in the atmospheres of five planets beyond our solar system, two recent studies reveal.
The five exoplanets with hints of water are all scorching-hot, Jupiter-size worlds that are unlikely to host life as we know it. But finding water in their atmospheres still marks a step forward in the search for distant planets that may be capable of supporting alien life, researchers said.
Gorgeous telescope timelapse makes you feel like you’re standing in Chile
As the chill of winter settles into the northern hemisphere, fantasies of down-south travel pervade a lot of people’s dreams. Well, here’s a virtual journey to warm climes for astronomy buffs: a beautiful, music-filled timelapse of several European Southern Observatory telescopes gazing at the heavens in Chile.
Uploaded in 2011 (but promoted this morning on ESO’s Twitter feed), the timelapse was taken by astrophotographers Stéphane Guisard (also an ESO engineer) and José Francisco Salgado (who is also an astronomer at Chicago’s Adler Planetarium.)
Saturn’s hexagon is a persisting six sided cloud pattern around the north pole of the planet. It is created by a band of upper-atmospheric winds, and the sides of it are about 13,800 km (8,600 mi) long, which is longer than the Earth’s diameter. There’s a hurricane swirling within the hexagon.
An animation of the hexagonal storm present on Saturn’s north pole. The hexagon is 30,000 kilometers across and has constant winds of more than 300 kilometers per hour. Images acquired by the Cassini spacecraft on December 10th, 2012.
Astronomers discover a planet that shouldn’t be there
An international team of astronomers has discovered the most distantly orbiting planet found to date around a single, sun-like star.
Weighing in at 11 times Jupiter’s mass and orbiting its star at 650 times the average Earth-Sun distance, planet HD 106906 b is unlike anything in our own Solar System and throws a wrench in planet formation theories.
In the constellation of Leo 33.1 light years away, a Neptune-sized planet orbits a red dwarf star at a distance of 4.3 million kilometres—15 times closer than Mercury is to our sun. It’s no surprise that the planet, Gliese 436 b, has an incredibly hot surface temperature of 439 degrees Celsius, but it’s definitely a surprise that the planet is also covered in ice. Since the boiling point of water is 100 degrees Celsuis, it seems impossible for ice to exist, but Gliese 436 b’s ice isn’t exactly conventional ice as we know it on Earth. It’s a phenomenon called “hot ice”, or “ice ten”—a kind of hot, solid water. It looks a lot like our ice, but if you touched it, it would pretty much melt through your flesh. It’s not kept in a solid state by a low temperature; instead, the planet’s gravity is so powerful that it pulls all its water vapour towards the core, forcing it together into a densely-packed, solid, hot layer. Even the incredibly hot temperatures can’t evaporate or melt it. Since the ice alone isn’t enough to account for the planet’s estimated radius, it’s thought that on top is an outer layer made up of hydrogen and helium. It’s puzzling, though, because planets with hot, hydrogren-dominated atmospheres are predicted to have significant amounts of methane and no carbon monoxide—but on Gliese 436b, it’s the other way around, and we have no idea why yet.
Will Life on Planets of Red Dwarf Stars be Older & More Evolved?
“We thought we would have to search vast distances to find an Earth-like planet. Now we realize another Earth is probably in our own backyard, waiting to be spotted,” said Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA). Six percent of red-dwarf stars have habitable, Earth-sized planets, astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) have found. Red dwarfs are the most common stars in our galaxy; about 75 percent of the closest stars are red dwarfs. The closest Earth-like planet could be just 13 light-years away, Harvard astronomer and lead author Courtney Dressing calculated.
Red dwarf stars are smaller, cooler, and fainter than our Sun. An average red dwarf is only one-third as large and one-thousandth as bright as the Sun. The cFa team culled the Kepler catalog of 158,000 target stars to identify all the red dwarfs, then reanalyzed those stars to calculate more accurate sizes and temperatures. They found that almost all of those stars were smaller and cooler than previously thought.
Locating nearby Earth-like worlds may require a dedicated small space telescope, or a large network of ground-based telescopes. Follow-up studies with instruments like the Giant Magellan Telescope and James Webb Space Telescope could tell us whether any warm, transiting planets have an atmosphere and further probe its chemistry. Since red dwarf stars live much longer than Sun-like stars, this discovery raises the interesting possibility that life on such a planet would be much older and more evolved than life on Earth.
Courtney D. Dressing, David Charbonneau, The occurrence rate of small planets around small stars, The Astrophysical Journal, 2013, in press
Daily Galaxy via Harvard-Smithsonian Center for Astrophysics