Daily Archives: 16/04/2010

The moon and the magnetosphere

Taken from the youtube channel of Astronomy Now magazine, an interview carried out at the National Astronomy Meeting with Sheila Kanani of the Mullard Space Science Laboratory, UCL, talking about the effect of Saturn’s moon Enceladus on the planet’s magnetosphere:


More water on Mars?

Another water on Mars story is out, this time focusing on the appearance of some gullies. These gullies appear to be being formed by processes that are more liquid than dust. Normal Martian gullies come about from carbon dioxide ice sublimating away and allowing dust in it to fall down a nearby slope. These tend to widen as the dust falls down and end in fan shapes. The new gullies start of slender and remain so. They also stop suddenly and then occasionally get restarted (these things are forming even now as seen by satellites orbiting Mars, snapping away at the same areas over weeks).

Water isn’t the only liquid that could be doing this and it certainly couldn’t last long on the surface if it was popping up, but there’s a chance something is causing it to well up. Another interesting area of study from the Red Planet.

The final thirteen

As well as truncating the shuttle program, NASA also truncated the shuttle crew, reducing it from seven to six from STS-132 onward. This means that the combined crews of the International Space Station and the space shuttle Discovery’s STS-131 is likely to be the last time thirteen people live on the ISS.

The last big ’13’ to be in the space news at the moment, Apollo 13, continues to be remembered on its fortieth anniversary with a series of 13 Things that save Apollo 13 on Universe Today with ‘Navigating by Earth’s Terminator‘.

For those looking forward already to the next of the shuttle missions, third to last of them, a tweet-up is to be held in Florida. 150 people selected at random from those who register with NASA will meet the crew and hopefully watch the launch over a two day event on May 13th-14th. Offer open to twitter users who follow @NASA.

Ash Update

With travel disruption likely to continue until tomorrow morning at the earliest, the ash cloud continues to dominate the news and twitter, via the #ashtag. An eruptions expert blogs here on the events. The UK’s main ash monitoring plane happens to be undergoing maintenance at the moment, but there is another one up keeping an eye on that stuff. Meanwhile ESA satellite images have provided an animation of the ash concentrations moving south-east. Not much seems to have hit here, but the glancing blow we did get seems to have produced some minor optical effects. Not quite “the most spectacular sunsets ever”, but an added tinge and the occasional solar halo.

Other things that may be visible as the Sun goes down (or thereafter) Venus, the Crescent Moon and the Pleiades all lined up in the west and possible meteor activity afterwards.

This Saturday is Earth day, which is quite lucky given everyone seems concerned with levels of a pollutant in the air at the moment. NASA’s doing events on the Washington Mall. ESA have pointed people towards its Earth Observation Webpage. To help with both that day and the ash at the moment, NASA have a page on different aerosols. Meanwhile, if you’re worried by how much CO2 the volcano is pumping out, don’t be, it is more than offset by the cancellation of European flights. European airspace is pumping out more than 200,000 tonnes less than before, and those flights still going are putting out more than the volcano.

Volcanic sunsets and the Crescent Moon

With the eruption of volcano Eyjafjallajoekull in Iceland causing disruption to UK controlled airspace (flight radar readout here) and with potential problems for the climate, it should be comforting to hear that there are good things to come out of this too – like volcanic sunsets. And we didn’t get it quite as bad as it has been in the past, either.

The ash pouring out of the volcano and into UK skies should greatly enhance the colours of sunsets normally seen. If you were looking out tonight, then the sunset should’ve given birth to a one day old Moon, just next to the planet Mercury and to the right and well below the altitude of Venus. Mercury will vanish from sight after this, but the crescent Moon and the sunsets should stay for the weekend. Reports are coming in that the eruption feeding the cloud is intensifying, though there’s no sign of an eruption of the far larger nearby volcano Katla, which normally accompanies these things. Tours of the erupting area have been canceled as the ash blocks out the Sun.

In Kendal it was pretty cloudy at the time of sunset, but then everything rapidly cleared. Stuart Atkinson then had a good evening’s planet watching, with a little hint of the vaguest bit of ashen sunset, but none of the golds and greens associated with more intense volcanic sunsets. On the other hand William Hay over in the Vale of Clwyd saw this:

Like Stuart, I saw nothing like that, but I did manage a snap or two of Venus, Mercury and the Moon. Here’s one of them:

Some pictures of the ash cloud are here. Latest on travel are here. Why pilots need to be aware of the ash is here. A European Space Agency satellite picture of the spreading ash cloud is here. The inevitable political cartoon to coincide with the UK Prime Ministerial TV debates is shown below:

More NAM stuff

I’ve been picking off bits of news coming out of the National Astronomy Meeting, 2010 in Glasgow, mostly using the NAM2010 Live Blog supplied by Astronomy Now magazine.

I begin with the deep mysteries and awe striking beauty that is of course Keith Cooper. Astronomy Now has a set of photos on facebook, which includes their intrepid reporters and editor. Plus a photo of a staircase.

Most the talk at NAM seemed to be about volcanic ash (which had shut down the airports, rather unhelpfully for those getting to and from the meeting, and which might’ve provided a nice sunset up there). But there were a few on stellar remnants too.

Neutron stars are the crushed cores of massive stars that have exploded in supernovae. One known star is Cassiopeia A, the youngest neutron star in the galaxy, which exploded sometime in the 17th century. At the point of explosion, these things are expected to be billions of degrees in temperature, but observations of the remnant in x-ray emissions using the Chandra x-ray space telescope, have shown it to have cooled to two million degrees. A campaign of observations over two years then showed the temperature drop by three percent. It is believed that nuclear processes are producing neutrinos that then carry away energy from the system, causing the cooling.

The star V838 Monocerotis, which became extremely luminous during an outburst in 2002 captured by the Hubble Space Telescope has become extremely cold for a star (indeed as cool as a brown dwarf, the object between planetary and stellar masses). It is believed, eight years of observations later, that the outburst and cooling are both due to a violent merger between two stars. Gravitational interactions would’ve torn away the outer layers, and the expansion would’ve both cooled them and made their surface area and therefore total luminosity far larger. Now indications from the Chandra x-ray space telescope are that things have settled down and the photosphere is coming back together in one big, hot object.

Finally, it would be remiss of me to have an Astronomy Now heavy post with no mention of Nick Howes and his latest splitting comet (following Siding Spring), McNaught. Images from their youtube channel are below:

More and less for exoplanets

Scientists in California have devised a method for stabilising the light of a star enough to block it and image exoplanets with smaller than previous telescopes. The planets around star HR 8799 had previously been imaged with an eight and a ten metre telescope, but the technique allowed a 1.5m telescope to perform the same feat. The twinkling of the star was first stabilised with adaptive optics and then suppressed using a coronagraph. The scientists now aim to upscale the technique allowing telescopes like the eight-ten metre ones to image more difficult exoplanetary targets. Imaging planets around stars is exceptionally difficult due to the sheer brightness of the shining central bodies compared to their smaller reflective partners.

…and it seems we’ll need every technique available if ground based telescopes are to compete with space based ones in exoplanet spotting. The Kepler space telescope team have won approval to hide data on potential planets until they’ve had a chance to confirm it for themselves, rather than allow others to confirm the observations, despite there being no truly comparable instruments scanning that part of the sky.

It seems those hoping for habitable exoplanets may be forced to turn to other means to speed things up. SETI is one possibility, but WETI is probably the number one choice for those hoping for alien contact.

Even without aliens, however, there have been some strange flashes in the sky. Fireballs above Wisconsin were captured by the  webcam of the Atmospheric, Oceanic and Space Science Building, Madison. The meteors are likely to be early members of the Lyrid meteor shower, remnants of Comet Thatcher.

But if you’re looking for more creative aliens, how about those that create strange regular features on planets – like the hexagon at Saturn’s north pole. Researchers at Oxford University have been spinning water round and round with die in it to show that such strange apparitions are just the result of fluid dynamics in a spinning gas giant like Saturn: