Monthly Archives: September 2010

Planet found in an alien star’s habitable zone

Gliese 581 is a name well known and repeated in exoplanetary circles. Lying 20.3 light years from us in the constellation of Libra, it is a red dwarf star now known to have at least six planets. Twice before, the star has been in the news with one of its planets declared close to the habitable zone – the slender band of orbits around the star where the stellar radiation is high enough to melt ice, but low enough not to boil water. Planet C was close, but on the hot side, too close to the star. Planet D was close, but on the cold side. Now a planet G has appeared and it is right in the middle of the habitable zone.

Appearing in this region around a star is not in any way proof that a planet can support life, it is merely a suggestion that it is likely to fulfill at least one of the prerequisites – the balance of radiation from its host star is sufficient to sustain liquid water. But further properties derived from observations of the star are quite positive. The planet is 3-4 times the mass of the Earth, suggesting a rocky planet with a defined surface, which at a similar density would put it at 1.2-1.4 Earth masses, giving a surface gravity not that dissimilar to our own. That would imply sufficient gravity to hold an atmosphere. But the similarities with the development of our own world do seem to end there.

The planet orbits its host star in 37 days. The low luminosity of Gliese 581 means that to be in the habitable zone in terms of radiation, the planet must crowd close to the star. This means the star has sufficient gravitational effect to tidally lock its satellite – meaning as with the Moon in orbit of the Earth, the same face of the planet always points toward the star. This would imply a searingly hot one face and freezing cold dark side, with winds racing from one side to the other. At the day night boundary, buffeted by these winds, more moderate climates would be seen at the different latitudes, where life could start, possibly evolving to take advantage of less temperate spaces on the planet after leaving the cradle. Red Dwarfs are long lived stars, so the time will also be there to do it.

But gravity and photons aren’t all a star can put out. Gliese 581 isn’t a flare star, that is, it isn’t known for sudden massive bursts of material from its surface, but it will still lose mass through slow stellar winds. It is believed that planets in close orbits to their host stars tend to lose their magnetic fields, or see them closely affiliated with that of their host stars. The protective magnetosphere, the magnetic sheath that protects us against the particle radiation that results from hot matter essentially expanding off the surface of our Sun, may not be replicated in this new place.

Whether or not there is life in this increasingly diverse place, the careful measurements carried out by the team, who measured the Doppler shifts of the light from the wobbling star to an amazing precision, do show that pulling out rocky planets in the habitable zones is within reach of modern technology. However, with the actual light from the planet lost in the glare of the star, it will take time and new technology to tease out the signal of life within that light, should it be there.

The paper announcing the discovery of the planet is here and one submitted at the same time detailing modelling of planet D’s atmosphere to determine whether or not its properties are sufficient to insulate the bitter cold and foster life is here.

Further reports on the story are here, here and here.

Lost Apollo 11 footage found… and released a year ago.

Space and physics news tends to consist of many, many small sparks of inspiration doing the rounds and dying down for a bit. So many, that occasionally, should a spark previously lost amid a sea of news activity re-emerge in times of lower headline flux, it can be mistaken for new news.

A few websites such as Discovery picked up on the story of new cleaned up footage of the early moments of Apollo 11, thought lost by NASA, but recorded by other stations. The reports state the footage has been painstakingly reassembled. All this is true, except for one minor problem – the footage was released during the 2009 celebrations of 40 years since the 1969 missions, as Universe Today noted.

ISS crewmembers land successfully

Three crewmembers from the International Space Station have successfully undocked from the station and landed in Kazakhstan in vehicle Soyuz TMA-18. The event brings to an end the crew configuration known as Expedition 24. The new crew configuration, Expedition 25, will commence when three new crewmembers join the three still on the station. This is expected to happen on the 9th of October, with the arrival of Soyuz TMA-01M.

The Soyuz undocked at 03:02 BST today. It carried out a separation burn to put distance between it and the station. At 05:31, it performed a four minute twenty one second deorbital burn, slowing it down sufficiently to drop out of the skies. The three segments of the vehicle separated at 05:56 and the crew continued towards the ground in the descent module, which entered the atmosphere at 05:59. It landed near Arkalyk, in Northern Kazakhstan, at 06:23. Pictures like the one shown below are at NASA’s flickr photo stream:

Events were also captured on NASA TV and archived to their youtube channel, from which the following, showing the change of command, the aborted landing, farewells and the actual undocking and landing, were taken:

Quick Observing report

The cold air tonight reminded me that there actually sometimes is a starry sky above my head. Seeing the clear, star pricked night, I assembled the Celestron 130SLT and eyepieces and quickly set it up outside. Not quick enough as a band of fast moving cloud headed between me and the targets. Defeated, I returned inside.

Not too long afterward, I returned and set up under a clearer sky with slower clouds. I took with me the Greenkat spotting scope as well. My three intended targets for the night were Jupiter, Uranus and the Comet 103P Hartley, which is breaching the magnitude 6.5 according to Heavens Above (finder chart here). My intention was to direct the main telescope straight onto Jupiter and Uranus and use the spotting scope’s wider field of view to scan for the comet before zooming in on it later, as I have done with previous ones.

This didn’t go quite to plan as a combination of the strong light of the Moon and neighbours popping by for a look meant the comet hunt was eventually called off. Although I did get a glimpse of Hartley, it didn’t seem quite good enough for a swing round of the Celestron.

Instead I concentrated on the brighter objects, taking in the turquoise Uranus before showing off Jupiter and the four Galilean moons to four neighbours. Three of the satellites were arranged in a similar way to the handle of the plough, all on one side of the planet. The fourth, Io, sat just off the limb, easily resolvable in the 9mm and 4mm eyepieces, but too close for the 24mm one to pick out. Just passed opposition, the giant planet is enormous in the eyepiece. As well as the remaining equatorial band, detail could be seen of the zones and caps, which is quite unusual for me to spot.

After this, a neighbour wanted to look at the just passed full Moon, so we swung onto that, with views of shadowed craters on the limb to see. With that done and the cold biting into everyone, the session was wrapped up and we headed back into our houses.

IYA2009 update

Some news on the ever continuing International Year of Astronomy, 2009.

The World At Night photography project has released a book of its best images as well as photography articles. Magic of the Stars is only presently available in German and Dutch, but may be translated to other languages soon. Meanwhile, their regular newsletter has been released – this time in English.

Global Hands On Universe and the Galileo Teacher Training Project have also released a joint newsletter on their efforts to spread good practise in astronomy education. The next ESA GTTP session will be held during the 7th-10th of December in the Netherlands. Teachers of students aged 11-19 will be encouraged to apply from the 1st of October. Full details here.

A forthcoming conference will examine the interaction between the New Media and Learning to determine best practise and how to go forward, using one to compliment the other. The event will take place in Brussels on the 25th and 26th of November. Details here.

And finally, the International Astronomical Union will be hosting a Middle East and Africa Regional meeting on the 10th-15th of April 2011, in Cape Town, South Africa. The meeting will discuss the use and opportunities afforded by new facilities in the region. Full details here.

Outreach funding deadline approaches

A funding deadline approaches for large outreach projects. The UK Space Agency is looking to award up to £5,000 to projects that will bring space to the masses. The total amount to be distributed is £35,000 and the deadline for applications is the 1st of October. Details on eligibility and the sort of projects funded last year are available here, along with all forms required for a successful submission.

Want to get back to basics in astronomy?

The British Astronomical Association is holding a basic introduction to astronomy session in Cardiff on the 16th of October. The series of talks and discussions on techniques will take place from 9:30am-6pm. Further details on cost, how to book and venue are here.