What's Up In Space? Martian mystery plumes, a stellar close-call and 85 years after Pluto's discovery, a spacecraft spies its tiny moons

Wednesday, February 18, 2015, 5:16 PM - What's up in space this week? Mysterious plumes on Mars baffle scientists, a close-call of stellar proportions and on the 85th anniversary of the discovery of Pluto, NASA's New Horizons spots two of its tiny moons.

Mystery Mars plumes

Astronomers have spotted something rather strange on Mars, and it's not faces in the dirt this time.

This animation was captured by astronomer W. Jaeschke on March 20, 2012, showing a strange feature in Mars' atmosphere - a large plume extending over 250 kilometres up into the atmosphere near the north polar region (indicated by the arrow).

Jaeschke gathered followup observations the next day, and along with fellow astronomer D. Parker, captured the feature in closeup detail, or at least as close as they could get, imaging it from telescopes here on the ground.

They weren't the only ones to spot these unusual features, either. A thorough search of Hubble's pictures of Mars between 1995 and 1999, and a similar search through amateur astrophotographs from the past 13 years, turned up other instances, including one from 1997 where Hubble managed to catch a similar high-altitude plume closer to the planet's equator.

What is this plume, and what's causing it?

Scientists aren't sure, but they have a few ideas.

These could be reflections from water-ice clouds, carbon dioxide ice clouds, or possibly dust. However, according to the scientists studying this, that explanation doesn't really fit into what's known about how clouds form at high altitudes.

They could be linked to Martian auroras, which are known to form in the same regions these plumes have been spotted - those where small-scale regional magnetic fields extend above the surface to interact with charged particles from the solar wind. What that connection could be, though, is apparently unknown.

For now, the mystery will have to endure, unless more instances can be spotted by astronomers on the ground or with Hubble, so that there's more to go on to study them.

Fortunately, the ESA may provide the clues to solve the mystery, with the launch of their ExoMars Trace Gas Orbiter mission, scheduled for January 2016.

Source: ESA

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A prehistoric close call of stellar proportions

Out in space, somewhere around 20 light years away from us (give or take a few light years), is Scholz’s star, a binary star system composed of a dim red dwarf star and an even dimmer brown dwarf orbiting it.

Credit: Michael Osadciw/University of Rochester

While perhaps not very remarkable in their own right, astronomers plotting the direction and speed of this pair have made a rather interesting discovery.

Trace the two back 70,000 years and they're only about 8 trillion kilometres from us (or about 80% of a light year) away from our Sun - the closest any star astronomers have found has ever come to us. What's more, is that puts the pair passing through our solar system's Oort cloud, the spherical collection of icy objects orbiting around the Sun.

Would that be (or could it still be) a danger to us? Most likely no. 

Running through 10,000 simulations of the flyby, taking all the factors and uncertainties into account, the astronomers found that only there was only one scenario where the pair passed through the inner Oort cloud, where objects are close enough together that they'd have been perturbed by the flyby, and possibly produce a 'comet shower' through the solar system. Those are pretty long odds for this flyby, but the astronomers do point out that there could be more of these dims stars close by, and the ESA may come to the rescue for this too, with their star-mapping Gaia satellite.

Source: University of Rochester

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85 years later, New Horizons spots two of Pluto's tiny moons

On Feb. 18, 1930, astronomer Clyde Tombaugh discovered Pluto, adding a new member to our solar system's family, and now, 85 years later, NASA has released pictures from their New Horizons spacecraft, revealing images of two of Pluto's moons orbiting around it.

Credit: NASA/Johns Hopkins APL/Southwest Research Institute

These two seven-frame animations combine new images of Pluto and Charon, taken between Jan 27 and Feb 8, 2015, that reveal the two largest objects orbiting the pair - Hydra (yellow diamond) and Nix (orange diamond).

"It's thrilling to watch the details of the Pluto system emerge as we close the distance to the spacecraft’s July 14 encounter," John Spencer, a member of the New Horizons team from the Southwest Research Institute, said in a NASA press release. "This first good view of Nix and Hydra marks another major milestone, and a perfect way to celebrate the anniversary of Pluto's discovery."

The spacecraft is still too far away to see tiny Kerberos and Styx - the smallest and newest discoveries in the system - and it will also still be some time before we get any detailed looks at any of these objects.

However, we don't necessarily have to wait four and a half months to get an idea of what this system could look like.

Check out this very cool graphic pieced together by Emily Lakdawalla, Senior Editor and Planetary Evangelist for The Planetary Society.

Credit: NASA/JPL/SSI chart by Emily Lakdawalla. Used with permission.

Taking various moons of Saturn, imaged by the Cassini spacecraft between 2005 and 2010, and resizing them to varying degrees, she has pressed them into service as a proxy for the Pluto system.

Pluto and Charon (played here by Rhea and Dione, respectively) are certainly large enough to reach hydrostatic equilibrium, meaning that their gravity is strong enough to compact them into a roughly spherical shape. They would likely have icy, dusty, cratered surfaces like Rhea and Dione as well (although the exact details and colouration will undoubtedly be different).

The other members - represented by Saturn's F-ring shepherd moons Prometheus and Pandora, and tiny 'trojan' moons, Helene and Telesto - are much smaller, though, and too small for their gravity to compact them into spheres. Their individual shapes could vary quite a bit, depending on what conditions were like when they formed and what kind of 'trauma', if any, they've endured since (Lakdawalla is putting her money on 'potatoes').

We won't know for sure until New Horizons is much closer to its flyby, but there's a good chance that Lakdawalla has chosen her proxies quite well.

Sources: NASA | Emily Lakdawalla, The Planetary Society.

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