Look west in twilight this Friday and Saturday (February 20th and 21st), and an unusual astronomical sight will await you.
Brilliant Venus and faint Mars will be paired remarkably close in the sky. And on Friday evening, the crescent Moon joins them in a tight bunch, a beautiful sight. On Saturday Venus and Mars appear even closer together, with the crescent Moon now looking down on them from above.
When it comes to “eyeball astronomy,” nothing is more satisfying than to see a pair of celestial objects appear close together in the sky, what astronomers call a conjunction. And 2015, notes Sky & Telescope’s longtime contributing editor Fred Schaaf, truly deserves to be called the “Year of the Conjunctions.” In January we watched Venus and Mercury come together in the evening twilight, and now comes a similarly close pairing of Venus and Mars. On Saturday they’ll appear 1/2° apart for viewers in North America. That’s about the width of a pencil held at arm’s length.
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In chambers that mimic Mars’ conditions, University of Michigan researchers have shown how small amounts of liquid water could form on the planet despite its below-freezing temperatures.
Liquid water is an essential ingredient for life as we know it. Mars is one of the very few places in the solar system where scientists have seen promising signs of it – in gullies down crater rims, in instrument readings, and in Phoenix spacecraft self portraits that appeared to show wet beads on the lander’s leg several years ago.
No one has directly detected liquid water beyond Earth, though. The U-M experiments are among the first to test theories about how it could exist in a climate as cold as Mars’ climate.
NASA’s Mars Curiosity Rover has completed a Martian year –687 Earth days– this week. The vehicle travels through an arid and reddish landscape that was home to glaciers in the past. Ancient Mars held large quantities of water, yet its global hydro-geological cycles were very cold, so much so that they induced the presence of a giant ocean, partially ice-covered and rimmed by glaciers on the lower plains of the northern hemisphere.
Now, an international team of researchers has confirmed this global picture locally, on the Martian site where Curiosity is roving: Gale crater. “This crater was covered by glaciers approximately 3,500 million years ago, which were particularly extensive on its central mound, Aeolis Mons” points to SINC the lead investigator of the study Alberto Fairén, from the Centro de Astrobiología (INTA-CSIC) in Spain and Cornell University in the USA.
“However, at that time there were also rivers and lakes with very cold liquid water in the lower-lying areas within the crater,” adds the researcher, who highlights the fact that ancient Mars was capable of “maintaining large quantities of liquid water (an essential element for life) at the same time that giant ice sheets covered extensive regions of its surface”.
Comet Siding Spring will brush astonishingly close to Mars later this year – close enough to raise concerns about the safety of a fleet of spacecraft orbiting the Red Planet. But after observing Siding Spring through a satellite-mounted telescope, University of Maryland comet experts found that it poses little danger to the Mars craft. The spacecraft will be able to get an unprecedented close look at the changes happening to this “fresh” comet as it nears the sun – as well as any changes its passing may trigger in the Martian atmosphere.
Fresh comets like Siding Spring, which have never before approached the sun, contain some of the most ancient material scientists can study. The UMD astronomers’ observations are part of a two-year-long research campaign to watch how the comet’s activity changes during its travels.
“Comet Siding Spring is making its first passage through the inner solar system and is experiencing its first strong heating from the sun,” said UMD assistant research scientist Dennis Bodewits, lead researcher on the UMD astronomy team that used NASA’s Swift satellite to estimate the comet’s size and activity. “Comets like this one, which formed long ago and remained for billions of years in the icy regions beyond Pluto, still contain the primeval building materials of our solar system in their original state.”
The slopes of a giant Martian volcano, once covered in glacial ice, may have been home to one of the most recent habitable environments yet found on the Red Planet, according to new research led by Brown University geologists.
Nearly twice as tall as Mount Everest, Arsia Mons is the third tallest volcano on Mars and one of the largest mountains in the solar system. This new analysis of the landforms surrounding Arsia Mons shows that eruptions along the volcano’s northwest flank happened at the same time that a glacier covered the region around 210 million years ago. The heat from those eruptions would have melted massive amounts of ice to form englacial lakes — bodies of water that form within glaciers like liquid bubbles in a half-frozen ice cube.
The ice-covered lakes of Arsia Mons would have held hundreds of cubic kilometers of meltwater, according to calculations by Kat Scanlon, a graduate student at Brown who led the work. And where there’s water, there’s the possibility of a habitable environment.
“This is interesting because it’s a way to get a lot of liquid water very recently on Mars,” Scanlon said.
Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks. Their study, published April 17 in the journal Nature, shows that the atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year evolution of our solar system.
Heather Franz, a former University of Maryland research associate who now works on the Curiosity rover science team at the NASA Goddard Space Flight Center, led the study with James Farquhar, co-author and UMD geology professor. The researchers measured the sulfur composition of 40 Mars meteorites—a much larger number than in previous analyses. Of more than 60,000 meteorites found on Earth, only 69 are believed to be pieces of rocks blasted off the Martian surface.
The meteorites are igneous rocks that formed on Mars, were ejected into space when an asteroid or comet slammed into the red planet, and landed on Earth. The oldest meteorite in the study is about 4.1 billion years old, formed when our solar system was in its infancy. The youngest are between 200 million and 500 million years old.
Beautiful streamlined islands and narrow gorges were carved by fast-flowing water pounding through a small, plateau region near the southeastern margin of the vast Vallis Marineris canyon system.
Images captured on 7 December 2013 by ESA’s Mars Express show the central portion of Osuga Valles, which has a total length of 164 km. It is some 170 km south of Eos Chaos, which lies in the far eastern section of Valles Marineris.
Osuga Valles is an outflow channel that emanates from a region of chaotic terrain at the edge of Eos Chaos to the west (top in the main images). Such landscape is dominated by randomly oriented and heavily eroded blocks of terrain. Another example is seen at the bottom of this scene, filling the 2.5 km-deep depression into which Osuga Valles empties.