A Driving Instructor's Blog

Astronomy

A meteorThe Mirror has some handy advice for people who might want to watch the Lyrid meteor shower this weekend.

Apparently, you need to look up at the sky to see if it’s clear, because if it’s not you won’t see anything. Having established that it IS clear, you then need to keep looking up because that’s where the meteors will be.

I’m glad they told me that. I’d never have figured it out by myself.

Somewhat more relevant, other than the fact that it is the “second brightest star in the sky”, is that Vega is in the North East (the two stars on the handle side of The Plough point roughly towards it). The Mirror doesn’t mention that.

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Just regarding that last post about Rosetta, and one of the images I have shown again here:ESA - 67P from 16km

If you get the full sized image here, in the black sky to the middle left there is a small white dot that might be a star, a data glitch, or just an aberration on the optics. But look what happens when you blow it up:The anomaly - expanded

It’s a disk shape with several lobes around it. Here’s what happens when you adjust the contrast:The anomaly - processed

Is that strange or what? I’d have never spotted it if I hadn’t seen the comments under that photo.

No one else seems to have picked up on a possible UFO in this latest Rosetta image.


There’s bound to be a logical explanation. On the list of possible logical explanations, it being a real out-of-this-world UFO comes in somewhere at around the gazillionth position.

Mind you, it doesn’t half look like that photo in Independence Day when they first detect the aliens approaching.


Actually, it is definitely some sort of exposure artefact. Every time a star appears in any Rosetta image you see some sort of streaking and those lobe-like structures. In another image from the final descent you can see multiple stars and they all show the same features.

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The Rosetta probe went into orbit around Comet 67P/Churyumov-Gerasimenko in August 2014, after a 10-year journey which saw it travel more than 4 billion miles as it swung around Mars and Earth (three times) to pick up speed. Finally, a critical deceleration phase as it neared 67P slowed it from almost 800 metres per second to a more sedate 8 metres per second, after which orbit was established.

This in itself was an incredible feat, but there was more to come. In November 2014 Rosetta discharged a small lander, known as Philae, which landed on the comet’s surface. I suppose success is a relative term, since Philae’s system for attaching itself to the comet was – with hindsight – possibly a little too much the stuff of science fiction. The theory was based on the assumption that comets are merely big balls of ice with dirt mixed in, and Philae was equipped with explosive harpoons which were supposed to be fired into the surface on contact and hold it there while it used threaded feet to screw itself down. I don’t think anyone is 100% certain, but it was believed that the harpoons didn’t fire, and consequently Philae bounced back into space and landed again – this time in a location which was believed to be dark and shielded so that an erratic signal was received and the solar panels were unable to keep it powered up. Nevertheless, it did send back some photographic data before going silent for more than a year.Philae Found (ESA image)

It was believed that if Philae were to suddenly be exposed to sunlight again it would wake up, and that this might happen as the comet went around the Sun and the rotational axes shifted. This didn’t happen as planned, though a very brief signal indicating full functionality was detected before the Rosetta-Philae link was shutdown to conserve power in mid-2015. It wasn’t quite the end, because only a month or so ago Rosetta incredibly produced a picture (composite, above) which clearly showed Philae pretty much upside down and wedged under a rocky cliff.

In the end, Philae didn’t actually achieve much – if you don’t count actually touching down very nearly safely on something travelling at 34,000 miles an hour around 300 million miles away as an achievement in itself! It nearly worked – nearly, but not quite. It didn’t drill and analyse samples as was originally intended. And personally, I wouldn’t rule out the possibility that comets are not the big snowballs they’ve always been reckoned to be and are somewhat harder – such that when Philae’s harpoons fired, instead of penetrating as the theory said they should, they bounced off and the thrust pushed Philae back into space before the weak gravity pulled it back down and dumped it in a crevice (I’m just surmising, OK?) I mean, does this look like a “dirty snowball”?ESA - 67P from 16km

Rosetta has sent back many thousands of high resolution images showing incredible detail. It has also detected chemicals which arguably lend weight to a theory (panspermia) which was put forward in its most commonly understood form by Fred Hoyle and Chandra Wickramasinghe in the 1970s, and given some support by Stephen Hawking in 2009. Again, speaking personally, it has not showed that 67P is anything like what comets have always been described as being.

As Comet 67P passed around the Sun in 2015 and began to move away into space it was always known that it would eventually be too far away for Rosetta to remain powered and operational. They could have hibernated it until 67P came back again in about 7 years’ time, but the chances of Rosetta successfully coming out of hibernation were slim (it was not designed to withstand such conditions and the risk was great). The decision was made to land Rosetta on 67P instead – more or less a low-speed crash landing.ESA - 67P from 51m above surface

Well, that happened today, and the image above was captured just 20 metres above 67P (that’s just slightly less than the distance you need to be able to read a car number plate from for your driving test). Apparently, the comet is so far away now that the data transfer rate is only about the same as it was on the Internet when we used to rely on dial-up modems. The width of the surface shown in the image is about 2.5m – two or three adult paces.

This is Rosetta’s final image.

Rosetta’s signal was lost at 11:19 GMT.

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I’m still making the most of the clear weather, which is forecast to come to an end this weekend. The moon is almost at its third quarter and the angle of the sun is showing just how uneven the earth-facing side really is.The moon as it appeared on 3 October 2015

I bought a new tripod, and this one is much more solid and easy to adjust than the super-cheap one I was using.

I should point out that I’m only doing this because I was surprised at how much detail I could get when I when I did that test photo last week (before the eclipse). So I thought I’d experiment.

The picture below shows the same area of the moon (two craters, in particular) as they appeared at full moon last Sunday and subsequently up until tonight.Crater sequence

At full moon, the two craters I have outlined are barely discernible as the sun’s light falls directly on to them. As the sun’s position changes, the craters become progressively more visible as shadows are cast by their walls. The edge of what I think is the Mare Imbrium is also more sharply defined, and craters which weren’t even visible to begin with suddenly appear.

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Having seen the effect of the sun casting shadows across the face of the moon I took the opportunity to catch the latest phase tonight. The moon rises later each night, and it is quite low on the horizon – which led to this lucky shot.The tree got there first

Anyway, after moving away from the Silver Birch tree, this is the detail visible tonight.Moon as it appeared on 2 October 2015

I was brought up to believe that although there were craters on the moon, much of it – and certainly the front – was like a big dusty desert. Apollo mission photos did a lot to create this impression.Apollo 15 moon surface photo

When I was a child I used to have a telescope, but it wasn’t very powerful – as I’ve discovered the last week or so, much less powerful than the telephoto lens on my camera. With my telescope, you could just make out mountain ranges at the edge of the sun’s coverage, but little else. How times change.

The areas on the moon you think of as being quite featureless show up as being pocked by craters.The top part of the moon

Even the edges of the “seas” (or maria) are seen to cast shadows, suggestive of steep sides.The bottom part of the moon

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It’s a clear night and I couldn’t resist getting a few more snaps of the moon now that it is waning. It’s amazing how much extra detail you get when the sun starts casting shadows instead of just hitting square on, as it does when the moon is full.The moon on 1st October 2015

This one shows the top corner.Moon - top corner

This is the top middle corner.Moon - top middle

Here’s the lower middle.Moon - lower middle

And finally, the bottom.Moon - bottom corner

At this rate, I’ll need to grow a beard and buy some horn-rimmed glasses.

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I stayed up late last night to watch the eclipse. Here are some of the photos I took. First of all, the moon at around 10.30pm Sunday (before anything had started):Moon - 27/9/2015 approx 10.30pm

Now, the moon at about 1.20-am Monday morning. There was a hint of something in the top left, though it isn’t easily seen in the photo:Moon - about 1.20am Monday morning

This next one is at around 1.40am. Definitely something happening now but still not easily discernible on the photo:Moon - about 1.40am Monday morning

Now, the appearance at about 2.10am Monday. Absolutely no mistaking it now:Moon - approximately 2.10am Monday

This one is from around 2.30am:Moon - around 2.30am Monday morning

This is at 2.55am. I’d left it a bit long and it had progressed further than I expected:Moon - around 2.55am Monday morning

I noticed that although the reddish tinge was visible to the naked eye, I was focusing on the lit part of the moon so was getting quite a fast exposure – meaning that the red part wasn’t showing up. This next image is from the same time (2.55am), but with my focus on the darker part. The lit part is over-exposed slightly as a result:Moon - approx 2.55am Monday morning, different exposure

By now, it had almost reached totality and over-exposure wasn’t as much of a problem. This is from around 3.15am.Moon - around 3.15am Monday morning

Here’s another from the same time, with the focus shifted slightly:Moon - approx 3.15am Monday morning, different exposure

And finally around 3.40am. I couldn’t stay up any longer as I had to go to work in the morning (note that exposure time was so long you can even see a couple of stars just to the right):Moon - approximately 3.40am Monday Morning

And another different exposure from the same time:Moon - around 3.40am Monday morning, different exposure

If I ever do anything like this again, I’ll check to make sure forecast times are in BST and not GMT – everything was an hour later than I’d expected!

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Anyone who is interested in this sort of thing will already know that Sunday night/Monday morning there will be a total lunar eclipse which coincides with a “supermoon” (where the moon is as close to the Earth as it gets, therefore at its largest). It’s quite a rare event, and another one isn’t due until 2033. The UK is also being dominated by high pressure at the moment, which promises clear skies.The moon as it appeared on 25 September

I’m planning to take some pictures of it, and if we DO get a clear sky then they should look like the one above. I took this tonight using a tripod and remote control shutter release with my Panasonic Lumix FZ200. You get an idea of how good this camera is for the price when you zoom in on the image a little.The lower left - showing Tycho, I think

If all goes to plan, I should be able to get a good set of images covering the eclipse.

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Here’s the first Philae image from the surface of Comet 67P/Churyumov-Gerasimenko (taken from the ESA website) by Philae – the small lander which touched down yesterday,First image taken by Philae from comet surface

It’s quite intriguing. After a lifetime of being told that comets are balls of “dirty snow” it looks pretty rocky. It also looks pretty solid, even though we’ve been repeatedly told it’s more like a big sponge since Rosetta arrived earlier this year.

It turns out that Philae’s fixing harpoons didn’t fire on landing, nor did its securing screws manage to bury themselves in the supposed icy surface. So it is just sitting there in a low gravity environment and – it would appear – on the edge of a steep drop. Fingers crossed that it stays put and does what it is programmed to do.

It also seems that when it first hit the ground (the one reported at around 4pm yesterday), it bounced hundreds of metres and took a further two hours to land again. Then, following a smaller bounce, it landed once more seven minutes later and finished in its current location.

Note that ESA images are larger than the one I’ve put here (I resize them to fit the page).


The latest news is that Philae eventually settled in the shadow of a cliff, and this may affect how well it can charge its batteries since the solar panels are not fully illuminated. One of its feet is apparently off the ground. The first bounce took it about 1km back into space before it landed again 2 hours later. After a smaller bounce, there is a suggestion that it is resting against a wall of some sort. It may even be lying on its side.

Although Philae weighs about 200kg here on earth, the very low gravity on 67P means that up there it only weighs about 1 gramme, so it could easily be thrown into space again, especially if comets vent anything like the one in the film Armageddon did. Having said that, one thing we HAVE discovered is that comets – this one certainly – are nothing like we have believed them to be for the last 100 years. There is also a worry that attempting to use Philae’s drill might move it, though this might be tried to positive effect when battery power begins to fail and all other data are obtained. Another possibility is that as 67P nears the sun then there may be more light and Philae will wake up.

You have to remember that there was only ever a 75% chance of success with the Philae part of the mission. Rosetta itself has achieved 100% of its goals, and if Philae never manages to drill, the images sent back by it mean that it has been successful beyond all realistic expectations. The entire mission has been the most spectacularly successful since Apollo 11 in 1969.

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I’ve been following the Rosetta mission with interest, and today it has reached its peak as the main Rosetta probe discharged a smaller probe – Philae – to land on the surface of Comet 67P/Churyumov-Gerasimenko.Philae seen from Rosetta shortly after release

The picture here (courtesy of ESA) is good enough – it shows Philae shortly after it was released by Rosetta to start its descent. Just imagine that this is happening around 500 million km away (it takes half an hour for the signals to reach Earth).

Some of the other images of the comet itself sent back by Rosetta have been incredible for their detail.

The mission overall has been impressive by virtue of the fact that Rosetta has bounced around the solar system for 10 years picking up speed and chasing down the comet, finally meeting up with it in August this year. The probe has travelled somewhere above 4 billion miles in total, and caught up with an object travelling at around 34,000mph and a third of a billion miles away!

And incredibly, after all that, Philae has successfully landed as of just after 4pm GMT on 12 November 2014! Well, half an hour before that, allowing for the signal transit time.

This really is an historic occasion (and I remember watching the moon landings when I was a child).

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