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Posted: 23-11-2012 19:34 Post subject:

OK, thanks. I doubt it'll come up in polite conversation anyway.

Posted: 24-11-2012 00:09 Post subject:

It's said MAH-kay-MAH-kay, apparently.
http://www.mikebrownsplanets.com/2008/07/make-make.html

News to me, anyway.

What I love about this observation is that the occultation was seen from several sites, hundreds of miles apart; each observatory saw a different slice of the occultation, so they could all be pieced together to get a good profile of the dwarf-planet as it passed over the star. It is not exactly circular, for instance.

Posted: 30-11-2012 09:57 Post subject:

Scientists discover frozen organic material on Mercury
Messenger spacecraft finds substances similar to tar or coal in craters on planet nearest sun
Associated Press in Cape Canaveral
guardian.co.uk, Thursday 29 November 2012 20.01 GMT

Despite searing daytime temperatures, Mercury, the planet closest to the sun, has ice and frozen organic materials inside permanently shadowed craters in its north pole, Nasa scientists say.
Earth-based telescopes have been compiling evidence of ice on Mercury for 20 years, but the finding of organics was a surprise, say researchers with Nasa's Messenger spacecraft, the first probe to orbit Mercury.

Both ice and organic materials, which are similar to tar or coal, were believed to have been delivered millions of years ago by comets and asteroids crashing into the planet.
"It's not something we expected to see, but then of course you realise it kind of makes sense because we see this in other places", such as icy bodies in the outer solar system and in the nuclei of comets, the planetary scientist David Paige of the University of California, Los Angeles, told Reuters.

Unlike Nasa's Mars rover Curiosity, which will be sampling rocks and soils to look for organic materials directly, the Messenger probe bounces laser beams, counts particles, measures gamma rays and collects other data remotely from orbit.

The discoveries of ice and organics, painstakingly pieced together for more than a year, are based on computer models, laboratory experiments and deduction, not direct analysis.
"The explanation that seems to fit all the data is that it's organic material," said the lead Messenger scientist Sean Solomon, of Columbia University in New York.
Paige added: "It's not just a crazy hypothesis. No one has got anything else that seems to fit all the observations better."

Scientists believe the organic material, which is about twice as dark as most of Mercury's surface, was mixed in with comet- or asteroid-delivered ice aeons ago.
The ice vaporised, then re-solidified where it was colder, leaving dark deposits on the surface. Radar imagery shows the dark patches subside at the coldest parts of the crater, where ice can exist on the surface.
The areas where the dark patches are seen are not cold enough for surface ice without the overlying layer of what is believed to be organics.

So remote was the idea of organics on Mercury that Messenger got a relatively easy pass by Nasa's planetary protection protocols that were established to minimise the chance of contaminating any indigenous life-potential material with hitchhiking microbes from Earth.

Scientists do not believe Mercury is or was suitable for ancient life, but the discovery of organics on an inner planet of the solar system may shed light on how life got started on Earth and how life may evolve on planets beyond the solar system.
"Finding a place in the inner solar system where some of these same ingredients that may have led to life on Earth are preserved for us is really exciting," Paige said.

Messenger, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, is due to complete its two-year mission at Mercury in March.
Scientists are seeking Nasa funding to continue operations for at least part of a third year. The probe will remain in Mercury's orbit until the planet's gravity eventually causes it to crash on to the surface.

Whether the discovery of organics now prompts Nasa to select a crash zone rather than leave it up to chance remains to be seen. Microbes that may have hitched a ride on Messenger are likely to have been killed off by the harsh radiation environment on Mercury.

The research is published in this week's edition of the journal Science.

http://www.guardian.co.uk/science/2012/nov/29/scientists-frozen-organic-material-mercury

Posted: 30-11-2012 23:17 Post subject:

Posted: 30-11-2012 23:54 Post subject:

Posted: 01-12-2012 05:17 Post subject:

This is a very good thing, since it means that Mercury could support a small colony. Of all the places in the Solar system, Mercury might be the most valuable. There we could use the abundant solar power to create large numbers of solar power collection satellites orbiting the Sun; eventually we could collect a significant porttion of the power output of the Sun, which would allow us to send spacecraft to nearby stars. All from a little organic ice on a dry planet.

Posted: 01-12-2012 10:45 Post subject:

Trouble is, your spacecraft would melt and you would be fried to a crisp and then frozen on the dark side.

Posted: 06-12-2012 08:36 Post subject:

Nearer to home:

Grail satellites show Moon's violent history
By Jonathan Amos, Science correspondent, BBC News, San Francisco

The scale of the battering the Moon received early in its history has been revealed in remarkable new data from two Nasa satellites.
Ebb and Flow - together known as the Grail mission - have mapped the subtle variations in gravity across the surface of the lunar body.
They show the Moon's crust to be a mass of pulverised rock - the remains of countless impacts.

Scientists say the beating was far more extensive than previously thought.
And this observation, they add, has relevance for the study of the Earth's ancient past.
It too would have been pummelled in the first billion years of its existence by the left-over debris from the construction of the planets.
It is just not obvious today because the Earth's surface has been constantly remodelled through time as a result of plate tectonics. All its early scars have long since healed.

"If you look at how highly cratered the Moon is - the Earth used to look like that; parts of Mars still do look like that," explained Prof Maria Zuber, Grail's principal investigator from the Massachusetts Institute of Technology, US.
"This period of time when all these impacts where [sic] occurring - this was the time when the first microbes were developing.
"We had some idea from the chemistry [of ancient rocks] that Earth was a violent place early on, but now we now know it was an extremely difficult place energetically as well, and it shows just how tenacious life had to be to hang on," she told BBC News.

Prof Zuber was speaking in San Francisco at the American Geophysical Union (AGU) Fall Meeting, the world's largest annual gathering for Earth and planetary scientists.
Her 300kg Grail twins have spent much of the past year mapping the Moon's gravitational field from an operational altitude of 55km.
The gravity differences they have been measuring are the result of an uneven distribution of mass across the lunar body.

Obvious examples at the Moon's surface include big mountain ranges or deep impact basins, but even inside the lunar body the rock is arranged in an irregular fashion, with some regions being denser than others.
All this has a subtle influence on the pull of gravity sensed by the over-flying Ebb and Flow satellites.

The Grail twins make their measurements by carrying out a carefully calibrated pursuit of each other.
As the lead spacecraft flies through the uneven gravity field, it experiences small accelerations or decelerations. The second spacecraft, following some 100-200km behind, detects these disturbances as very slight changes in the separation between the pair - deviations that are not much more than the width of a human red blood cell. Exclamation

And when the gravity measurements are combined with topographical information from another of Nasa's lunar satellites showing the surface highs and lows, it becomes possible to separate out that signal related just to the Moon's internal structure and composition.

The resolution of Grail's maps far exceeds anything previously achieved - a thousand to a hundred-thousand times' improvement.
This will be a boon to researchers as they study not just the general evolution of the body but how individual features on its surface formed - from the largest impact features like the ringed basins, right down to craters just 20-30km across.

One standout observation is that the Moon's crust - its topmost layer - ranges in thickness from 34km to 43km. These numbers are about 10-20km less than previously proposed.

"And because the Moon's crust is extremely important for understanding the bulk composition of the Moon, what these results show is that the bulk abundance of aluminium in the Moon is exactly the same as that in the Earth, whereas previous studies had suggested the composition of the Moon may be different from that of the Earth," said Dr Mark Wieczorek, a Grail co-investigator from the University of Paris, France.
"This is consistent with the hypothesis that the Moon is derived from materials that come from the Earth following a giant impact event."

The crust underlying a couple of major impact basins appears so thin as to be virtually non-existent. This suggests the impacts that rained down on the Moon may even have excavated the underlying lunar mantle at those locations.

The Grail team said that compared to the surface, the interior looks gravitationally very smooth. Indeed, 98% of the gravity signal measured by the satellite twins relates to the Moon's surface features, such as its crater rims and big mountains.

However, the data does point to the existence of long (up to 500km) linear structures that extend up from the interior of the body into the lower crust. The Grail team believes these to be buried dykes — formed from magma that seeped into large fractures in the crust, and then solidified into dense walls of rock.

This may hint at an early expansion phase in the Moon's history when the hot body expanded outwards, before eventually cooling and contracting.
"This had been predicted theoretically a long time ago but there was no direct observational evidence to support this early lunar expansion until this Grail data," said Dr Jeff Andrews-Hanna, a science team member from the Colorado School of Mines.

http://www.bbc.co.uk/news/science-environment-20617506

No hollow moon, no alien base? How disappointing! Wink

Posted: 07-12-2012 09:00 Post subject:

Dawn probe spies possible water-cut gullies on Vesta
By Jonathan Amos, Science correspondent, BBC News, San Francisco

Scientists say they have seen features on Asteroid Vesta that look as though they could have been cut by some sort of fluid flow - possibly liquid water.
If correct, it is an extraordinary observation because any free water on the surface of the airless body would ordinarily boil rapidly and vaporise.

But pictures of Vesta taken by Nasa's Dawn probe show complex gullies running down the walls of some craters.
The possibility of liquid erosion needs to be considered, say the researchers.
"We want to hear what other people's opinions are," Jennifer Scully, from the University of California, Los Angeles (UCLA), told BBC News.
"We're just putting it out there to the community; we're not suggesting anything hard and fast at this stage."
Ms Scully was speaking here at the American Geophysical Union (AGU) Fall Meeting, the largest annual gathering of Earth and planetary scientists.

The Dawn satellite spent more than a year investigating Vesta, the second largest member in the asteroid belt between Mars and Jupiter.
The probe departed the body this past September, but not before it had mapped most of the surface from an altitude of just 210km.
This allowed the Nasa mission to pick out surface features in fine detail.

Ms Scully examined all of the craters on Vesta that measured about 10km and wider, cataloguing the shapes of the gullies that etched their walls.
In the majority of cases (about 50 examples), the troughs trace simple descent lines and are presumably the consequence of loose rock or soil falling down the slope. But in a second, smaller group (11 examples), the pattern the gullies cut in the surface is quite different. They are complex; they are interlaced.

"The first group we call Type A. They're very typical of dry-mass wasting; the sort of thing you would get on Earth's Moon and on other, smaller asteroids. But the Type B gullies are the ones we think may have this liquid water origin; they have quite distinct morphologies. They are longer and narrower. They also interconnect, branching off one another."

If it was liquid water that carved these features, the question then arises as to its source.
Vesta is recognised generally to be a very dry body. Geological processes in its early history are thought to have driven off the vast majority of its volatile materials.

And in any case, with no pressure from an atmosphere, the asteroid cannot sustain liquid water at its surface for very long. Any such fluid would be lost to space in short order.
This means any reserve of water must be retained beneath the surface.

"[It] would be cool enough just a few metres or even some centimetres beneath the surface that water could be preserved for a long time," said Prof Chris Russell, the principal investigator on the Dawn mission. "So we have some mechanisms like comets that might bring water to the surface - then it could be stored for some period of time."

Perhaps that buried ice later melted and burst out; may be it was water bound up in the rock, in hydrated minerals, that was released by the heating associated with an impact at the surface.

In the near-equatorial Cornelia depression, for example, the Type B gullies tend to form in the dark material that dominates some areas of the crater.
It has been suggested this material is very similar to carbonaceous chondrite meteorites, which can contain a lot of water and the related hydroxyl (OH) mineral.
Could the impact that created Cornelia have temporarily increased local temperatures and pressures sufficiently to allow liquid water briefly to flow and cut the gullies before spontaneously boiling off?

The observations mirror those for Mars back in 2000 when satellite pictures also revealed complex gully systems running down the walls of craters on the Red Planet.
A fierce debate then ensued between those who argued they were water-cut and those who proposed other explanations that did not require water. One alternative proposed that the channels were cut by a tumbling mass of dry material suspended in a flow of carbon dioxide.

The controversy of the Martian gullies prompts Prof Russell to be cautious in the interpretation of the Vesta gullies.
"We want to be very, very sure on any statement or pronouncement we make about the gullies or water or anything like that, because it turns out that there are a lot of different interpretations - we have to work our way through them," he said.

"That's exactly how the scientific method works - we have an idea; we have to test it against the available evidence, and a lot of people are shareholders in that evidence and they will talk to us about what their evidence is," he told BBC News.

http://www.bbc.co.uk/news/science-environment-20582704

Posted: 08-12-2012 21:28 Post subject:

The latest Sky at Night is on iPlayer:

The Sky at Night
- Mercury and the Moon

The tiny planet Mercury is in the morning sky and Sir Patrick Moore talks about the latest news from Messenger, the spacecraft which is over Mercury at the moment. Mercury is often compared to the moon, which was last visited by man in December 1972. Forty years on, Dr Chris Lintott looks at the legacy of that mission, Apollo 17, and what it has been able to tell us about the moon.

http://www.bbc.co.uk/iplayer/episode/b01p65ql/The_Sky_at_Night_Mercury_and_the_Moon/

Available until
12:19PM Sat, 15 Dec 2012

There's also information about a chance for early birds to see Mercury in the morning sky this month. (I'm a poor sleeper, so I may try to spot it myself - if I don't have to go outside in the forecast freezing weather!)

There's also mention of an asterism that I've never heard of before, Kembles Cascade! It certainly seems worth getting the bins out for a peek at that!
http://en.wikipedia.org/wiki/Kemble%27s_Cascade

Sad to say, Patrick Moore is not getting any younger, and his once characteristic clipped manner of speech has become quite slurred, so Chris Lintott does most of the SaN voice-overs now.

I'm not getting any younger either, so this could be my last chance to see PM on TV, as well as the elusive planet Mercury in the sky - and Kemble's Cascade!

Posted: 09-12-2012 15:05 Post subject:

The Sky at Night link posted above is now Sir Patrick's last appearance on the show, as sadly he died today.

Plenty of obits on line, eg:
http://www.bbc.co.uk/news/uk-20657939 (with video).

Posted: 01-01-2013 13:03 Post subject:

A story I missed last week:

'Brighter than a full moon': The biggest star of 2013... could be Ison - the comet of the century
A comet discovered by two Russian astronomers will be visible from Earth next year. Get ready for a once-in-a lifetime light show, says David Whitehouse
David Whitehouse Thursday 27 December 2012

At the moment it is a faint object, visible only in sophisticated telescopes as a point of light moving slowly against the background stars. It doesn't seem much – a frozen chunk of rock and ice – one of many moving in the depths of space. But this one is being tracked with eager anticipation by astronomers from around the world, and in a year everyone could know its name.
Comet Ison could draw millions out into the dark to witness what could be the brightest comet seen in many generations – brighter even than the full Moon.

It was found as a blur on an electronic image of the night sky taken through a telescope at the Kislovodsk Observatory in Russia as part of a project to survey the sky looking for comets and asteroids – chunks of rock and ice that litter space. Astronomers Vitali Nevski and Artyom Novichonok were expecting to use the International Scientific Optical Network's (Ison) 40cm telescope on the night of 20 September but clouds halted their plans.

It was a frustrating night but about half an hour prior to the beginning of morning twilight, they noticed the sky was clearing and got the telescope and camera up and running to obtain some survey images in the constellations of Gemini and Cancer.

When the images were obtained Nevski loaded them into a computer program designed to detect asteroids and comets moving between images. He noticed a rather bright object with unusually slow movement, which he thought could only mean it was situated way beyond the orbit of Jupiter. But he couldn't tell if the object was a comet, so Novichonok booked time on a larger telescope to take another look. Less than a day later the new images revealed that Nevski and Novichonok had discovered a comet, which was named Comet Ison. A database search showed it has been seen in images taken by other telescopes earlier that year and in late 2011.
These observations allowed its orbit to be calculated, and when astronomers did that they let out a collective "wow."

Comet Ison has taken millions of years to reach us travelling from the so-called Oort cloud – a reservoir of trillions and trillions of chunks of rock and ice, leftovers from the birth of the planets. It reaches out more than a light-year – a quarter of the way to the nearest star. In the Oort cloud the Sun is but a distant point of light whose feeble gravity is just enough to hold onto the cloud. Every once in a while a tiny tug of gravity, perhaps from a nearby star or wandering object, disturbs the cloud sending some of its comets out into interstellar space to be lost forever and a few are scattered sunward. Comet Ison is making its first, and perhaps only visit to us. Its life has been cold, frozen hard and unchanging, but it is moving closer to the Sun, and getting warmer.

Ison's surface is very dark – darker than asphalt – pockmarked and dusty with ice beneath the surface. It's a small body, a few tens of miles across, with a tiny pull of gravity. If you stood upon it you could leap 20 miles into space taking over a week to come down again, watching as the comet rotated beneath you. You could walk to the equator, kneel down and gather up handfuls of comet material to make snowballs, throw them in a direction against the comet's spin and watch them hang motionless in front of you. Shocked

But it will not remain quiet on Comet Ison for the Sun's heat will bring it to life.

By the end of summer it will become visible in small telescopes and binoculars. By October it will pass close to Mars and things will begin to stir. The surface will shift as the ice responds to the thermal shock, cracks will appear in the crust, tiny puffs of gas will rise from it as it is warmed. The comet's tail is forming.

Slowly at first but with increasing vigour, as it passes the orbit of Earth, the gas and dust geysers will gather force. The space around the comet becomes brilliant as the ice below the surface turns into gas and erupts, reflecting the light of the Sun. Now Ison is surrounded by a cloud of gas called the coma, hundreds of thousands of miles from side to side. The comet's rotation curves these jets into space as they trail into spirals behind it. As they move out the gas trails are stopped and blown backwards by the Solar Wind.

By late November it will be visible to the unaided eye just after dark in the same direction as the setting Sun. Its tail could stretch like a searchlight into the sky above the horizon. Then it will swing rapidly around the Sun, passing within two million miles of it, far closer than any planet ever does, to emerge visible in the evening sky heading northward towards the pole star. It could be an "unaided eye" object for months. When it is close in its approach to the Sun it could become intensely brilliant but at that stage it would be difficult and dangerous to see without special instrumentation as it would be only a degree from the sun.

Remarkably Ison might not be the only spectacular comet visible next year. Another comet, called 2014 L4 (PanSTARRS), was discovered last year and in March and April it could also be a magnificent object in the evening sky. 2013 could be the year of the great comets.

As Comet Ison heads back to deep space in 2014 the sky above it would begin to clear as the dust and gas geysers loose their energy. Returning to the place where the Sun is a distant point of light, Comet Ison may never return. Its tail points outward now as the solar wind is at its back, and it fades and the comet falls quiet once more, this time forever.

http://www.independent.co.uk/news/science/brighter-than-a-full-moon-the-biggest-star-of-2013-could-be-ison--the-comet-of-the-century-8431443.html

Wow! That's someting to look forward to - it's years since I last saw a naked-eye comet. Cool

Comet C/2011 L4 PANSTARRS is already listed, with star maps showing its position (it's currently mag 12.8 in Scorpius) on http://www.heavens-above.com

(I think 2014 L4 (PanSTARRS) in the article is a typo, as this number usually refers to year of discovery! The perihelion of 2011 L4 (PanSTARRS) is given as 10.3.2013, which seems to agree with what the article says.)

Posted: 02-01-2013 15:55 Post subject:

Predictions of comet's brilliance often don't come true - anyone remember Comet Kohoutek? Still - fingers crossed! This could be a once in a lifetime sight.

Posted: 05-01-2013 09:09 Post subject:

Kepler planet survey starting to yield interesting results.

http://www.sciencedaily.com/releases/2013/01/130103143422.htm

It's starting to look like there are many many planets in our galaxy - and very few of them will be like Earth:

Posted: 07-01-2013 16:07 Post subject: