Flare in EV Lacertae
20 May at 22:58 by Wilson
One of the most important events in Greg Egan’s novel Diaspora happens when a pair of neutron stars in the constellation Lacerta collide, sending out a powerful gamma ray burst and causing the extinction of most life on Earth. I was reminded of that while reading, earlier today, about an unassuming, small red dwarf star in that constellation sending out a massive flare, thousands of times more strong than the ones our Sun sends out every now and then.
There’s no risk to us, of course, and Phil Plait does a much better job than I would be able to of telling the whole story; go there, it’s an excellent read.
Still, that’s one more way the universe can kill us all… (and I guess I’ll go reread Greg Egan’s novels…)
Lunar eclipse, 21 February
18 Feb at 15:28 by Wilson
Most people must have heard by now that there will be a total lunar eclipse later this week, on Thursday (or Wednesday, depending on your time zone). Unfortunately Australians will miss this one; it will be visible, at least in part, basically everywhere else but here (that’s not entirely true: Japan, most of China, southeast Asia, New Zealand and several Pacific nations will also miss it, but it’s close enough to the truth…).
The eclipse starts at 00:34 GMT on Thursday (11:34 ADST for those intent on following it online; or, for American readers, 19:34 EST or 16:34 PST on Wednesday — observers in the west coast of the US will see the Moon rise with the eclipse already in progress) and totality will go from 03:00 to 03:51 GMT (Thu 14:00-14:51 ADST, Wed 22:00-22:51 EST, Wed 19:00-19:51 PST). Full details are here.
For the record, Australian observers will see part of a partial (but almost total) eclipse on 16 August — the Moon will set for all of the country before the eclipse is over.
Annular solar eclipse, 07 February
5 Feb at 16:01 by Wilson
This Thursday we’ll have the first solar eclipse of 2008, but very few people will actually see more than a very small partial eclipse. It won’t be a total eclipse, but an annular one: this happens when the Moon is not large enough in the sky to cover the whole disk of the Sun (when seen from what would normally be the path of totality, the Sun will form a ring around the disk of the Moon).
The path of “annularity” covers just part of Antarctica and some areas of the southern Pacific; the annular phase starts at 03:20 UTC and ends at 04:30 UTC. A partial eclipse will be visible from eastern Australia, New Zealand and neighbouring island countries. From Melbourne, the eclipse will start at 2:38pm (local time) and end at 4:14pm; the maximum eclipse will happen at 3:28pm, but just a bit more than 8% of the Sun will be obscured, so it will be barely noticeable (and the forecast says it will be raining, anyway); add about 15 minutes to these times if you are in Sydney (and you’ll see just over 11% of the Sun being obscured). For more details and for information about other locations, see the excellent website of the Nautical Almanac Office of the UK.
NEVER LOOK DIRECTLY AT THE SUN, neither with your naked eyes nor with binoculars or telescopes unless they are correctly fitted with the proper filters; if in doubt, don’t to it.
Venus, Jupiter and the Moon get together
4 Feb at 16:40 by Wilson
If you happen to be up just before dawn tomorrow morning, look to the east for a beautiful show: Venus and Jupiter have been very close to each other for a few days already, but tonight the Moon joins them to make for a nice trio lighting up the sky before dawn.
The planets should be very easy to identify, even if you don’t know which side is east. Venus is now by far the brightest object in the sky and it is rising a few hours before the Sun; Jupiter is somewhat fainter but still brighter than almost anything else.
The Moon will be a very thin crescent, which probably will add to the show (a full Moon would “wash out” the brightness of Venus and Jupiter). Venus will be almost a full disk, but on a telescope it should be easy to see that it is not quite full (and Jupiter, of course, will be full, as always).
Watching Mercury
9 Jan at 16:16 by Wilson
Now is a good time to look at that small rock sitting very close to our Sun… Mercury is reaching it maximum eastern elongation, which means that it’s about as far away from the Sun (when seen from Earth) as it is going to get this time around. If you have a nice, flat western horizon, look for it soon after the sunset, slightly north of the place where the Sun disappeared. The sky will still be quite bright by the time Mercury sets, but the best day to see it will be on the 21st. For observers in Melbourne, Mercury will set at 21:41 today and 21:42 tomorrow (the Sun sets at 20:45 and 20:44, respectively). For other locations, check this page from the US Naval Observatory.
But, of course, you may prefer to watch it from a better vantage point. If so, now is a very good time: MESSENGER, the first probe to visit that planet since the late 70s, is less than one week away from its first fly-by. The closest approach, at just 200km from the surface, will happen on the 14th, but the cameras will start to take pictures of the planet tomorrow, and some images should be released soon afterwards.
MESSENGER was launched in August 2004 and is in a very complex and long trajectory that will end up with the probe in orbit of the planet… on 18 March 2011. Two more fly-bys happen before then, one in October 2008 and other in September 2009. The reason for this is that it is very hard to send a probe that close to the Sun without having it go into the Sun; it will use its several planetary fly-bys (two of the Earth, two of Venus and three of Mercury) to match its speed to that of Mercury, enabling it to enter the planet’s orbit with relative ease.
Mars Opposition
19 Dec at 10:46 by Wilson
Next Monday, 24 December (Christmas Eve), Mars (seen here in a composite image taken by the Mars Reconnaissance Orbiter last week) will be in opposition with relation to Earth; what this means it that the Sun, Earth and Mars will be in a straight line and Mars will be exactly in the opposite direction from the Sun as seen from the Earth.
Because of the way both planets orbit the Sun (at different distances and speeds), this happens approximately every two years, and this event marks the closest approach between the planets in that period. Depending on when that happens in the year, though, the approach can be very close, not so close or something in between. This year’s opposition falls in the “something in between” category. The 2003 approach was a really close one, as it happened when both planets were at their closest approach to the Sun (this always happens when the opposition happens in July or August); the next one, in early 2010, will be a “not so close” one.
Still, Mars is already very bright in the evening sky; maximum brightness, in fact, happens tonight, as the actual closest approach is not at the same time as opposition; since the orbits don’t quite match, the closest approach happens today (19 Dec) at 10.45am Melbourne time. Mars can be easily seen at night, even in bright skies, as a clearly reddish “star” rising in the north-east as the Sun sets (which makes sense, if you think about it). Even a small telescope will provide a very good view of the planet, but looking with your naked eyes will be a beautiful sight as well.
This great view will continue over the next few weeks, slowly losing brightness as Earth overtakes Mars and pulls away. So, lots of opportunities to go out and watch our red neighbour; if the weather is not that good tonight, you’re still sure to get at least one clear night over the next week or so. And, really, you can’t miss it in the sky.
Solar eclipse, 11 September
6 Sep at 17:01 by Wilson
As a few people probably know, there will be a partial solar eclipse next week, on 11 September, starting at 10:25 UTC (20:25 Melbourne time). It won’t, however, be visible from Australia; in fact, only people in South America (in locations at least 5 degrees south of the equator) and western Antarctica will see anything special. The UK’s Nautical Almanac Office has a great map and animation showing the path of the eclipse.
Eastern Australia will see some solar action next year, with a very small partial eclipse in mid-afternoon on 7 February (less than 10% of the Sun will be obscured). That will be part of an annular eclipse (a total eclipse in which the apparent size of the Moon is not large enough to cover the whole disk of the Sun, leaving a bright ring around the Moon), but the path of “annularity” touches only Antarctica and the South Pacific.
For the record, the next total eclipse visible from eastern Australia will be in July of 2028, and it will not be total for Melbourne (it will be for Sydney, though).
Eclipse night
29 Aug at 10:56 by Wilson
Despite threats from clouds covering the sky, the sky was bright and clear for most of the event last night, which made for great viewing conditions. At the start of the umbral phase of the eclipse, the eastern sky was completely covered from my location, so I missed that. It started clearing up around the time of totality, and the first time I managed to see the Moon (still covered by light clouds) it was already entirely in the dark, with a nice, dark red-orange colour.
It only got better from there as the clouds moved away, so that it was possible to see the whole process of the Moon moving out of the shade and getting progressively brighter. It was beautiful with the naked eye, and even better with binoculars: you could easily see the colour gradient across the lunar globe, and it looked distinctly tri-dimensional.
So, it was a good spectacle. The next one for us, unfortunately, won’t be until 2011. We will, however, have a partial solar eclipse next February; I’ll write more about it as we get closer to the date.
Up there and down here
22 Aug at 0:09 by Wilson
As I write this, space shuttle Endeavour is preparing to return to Earth, one day earlier than expected because of the approach of hurricane Dean. The worry is not so much about bad weather in Florida interfering with the actual landing, but with bad weather in Texas forcing the evacuation of the mission control buildings in Houston. I’m pretty sure everyone will be following the landing closely because of the aforementioned problems with the damaged heat shielding tiles, which NASA chose not to fix (as the process of fixing them could actually make the problem worse). NASA TV will have live coverage of the landing on the web in a few hours.
In unrelated news, the weather forecast for next Monday Tuesday in Melbourne calls for a mostly sunny day with a top temperature close to 20° (and even above 20, depending on your suburb). Great weather for the lunar eclipse of that night; remember that you can join the Astronomical Society of Victoria on the roof of the Victoria Gardens shopping centre, in Richmond, starting from 6:30pm: a gold coin pays for admission, and you get to use the viewing equipment that will be there to look at the moon and the rest of the night sky (I have no idea how to get on the roof, though; my guess is that one would use the garage lifts). But, of course, the only equipment you need to see the eclipse are your own eyes.
And, should you want to go out on the previous night, Mars and the red star Aldebaran will be very close together, presenting a nice show on the night sky to anyone who’s up and looking east around 3am; the bright stars Betelgeuse, Rigel and Sirius will not be far off, adding to the show. Mars will put on an even better show in December, at the time of its closest approach to Earth, but we can talk more about that then.
Lunar eclipse this month
8 Aug at 15:51 by Wilson
As I’ve mentioned before, there will be a total lunar eclipse later this month, visible from Melbourne (and from the Americas and most of Asia as well). The eclipse happens on Tuesday, 28 August, and starts at 17:52 Melbourne time (07:52 UTC), which is three minutes before sunset and nine minutes after the moon rises (here; check your local times). Eastern Australia will be able to see the whole eclipse (assuming a clear view of the eastern horizon from your location), while the west will see the moon rise with the eclipse already in progress. Totality starts at 19:52 (09:52 UTC) Melbourne time, and lasts for a bit over 90 minutes. Details and maps here.
That, of course, assumes that the rain gods will look kindly on us. Should we miss this one, the next total eclipse visible from here will happen in late 2011.
For those interested, the Astronomical Society of Victoria is organising a public viewing of the eclipse on the roof of the Victoria Gardens shopping centre (top deck of the car park, actually), and telescopes will be available to the public. I assume this event will only happen with good weather, but check the details closer to the date.
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