2003 UB313 on astro-ph

Astronomers publish technical papers in a slew of astronomical journals. Unless you have access to a university library, you are unlikely to read many - if any - of them and even then you will be reading things that are usually several months behind. A number of years ago, the arXive (pronounced 'archive') was set up as a free on-line library of physics, maths and computer science papers. The astronomy section is named astro-ph and it can be searched, has RSS feeds and now even allows limited trackbacks.

Spectra for 2003 UB313
A comparison of the spectra of 2003 UB313 and Pluto. Click for full-res (astro-ph paper). CREDIT: M.E. Brown, C.A. Trujillo, D.L. Rabinowitz
Anyway, I hadn't yet got around to reading the latest papers today, so Megan beat me to the discovery paper for 2003 UB313. The paper has been submitted to Astrophysical Journal Letters and details some of the scientific measurements. It turns out that Mike Brown et al. have found pre-discovery images back to 1989 and so have been able to constrain the orbit very well. They've worked out that it is currently near aphelion and will reach perihelion (38.2 AU) in the year 2257.

Spectral observations (see image) show that it resembles Pluto, but has some differences. The authors think that the nitrogen and methane may be segregated in the atmosphere of 2003 UB313 as it is so cold. As it moves closer to the Sun, the methane could become a bit more volatile and mix with the nitrogen making it look a bit more like Pluto. Time, and more observations, will tell. Read the paper for more details.

Posted in astro blog by Stuart on Wednesday 31st Aug 2005 (14:36 UTC) | Permalink

Eppur si muove

Jupiter and Moons
An animation of the planet Jupiter and four of its moons. CREDIT: Stuart/Chris
With Jupiter and Venus currently approaching each other on the sky (in reality they are about 750 million km apart), it prompted me to have a hunt through the limited selection of images that I've taken of the king of planets.

On the right you should see a short animation which Chris and I made on a cold November night back in 1999. We were observing with a Meade LX200 and thought we would try to make an animation of Jupiter's moons by taking a series of shots once every 15 minutes. We picked 15 minutes because that would give us time to look at other stuff between shots and we thought any more frequently would be overkill. At the outset we had no idea how many frames we would get because the weather isn't terribly reliable around here. It turned out to be one of the best nights of the winter and the best observing night I've had in the middle of Manchester. We observed Jupiter until it got too close to the horizon at around 4 am. To round things off we even managed to spot an Iridium flare in the dawn sky. I got no sleep that night and I had to attend five hours of lectures from 9 am. It can be difficult to concentrate on a physics lecture when you've been awake for 26 hours!

The following day, I loaded the images onto the computer and aligned them all by hand. I then inverted the colours (black on white is easier to see than white on black) and put them into an animation programme. I have added some labels to the first frame so that you see which moon is which (left to right: Callisto, Io, Ganymede and Europa). The vertical band is due to the fact that Jupiter was so bright - so many electrons were liberated in the Jupiter pixels of the CCD, that they overflowed into neighbouring pixels in the readout direction (up and down).

The frames aren't of the highest quality but I love the fact that you really can see the moons move around Jupiter - recreating one of the famous observations of Galileo. I'm sure there are some of you out there with better telescopes and/or clearer skies than I had. So I challenge you to do this yourself.

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Posted in astro blog by Stuart on Wednesday 31st Aug 2005 (09:48 UTC) | Permalink

NGC 6559

Staying in the southern hemisphere, here is another new image this time taken by the Gemini South telescope. It isn't a Chinese dragon but the cool, dark dust cloud NGC 6559. The cloud doesn't emit its own optical light so we can only see it in this image because it is absorbing light from a more distant cloud of ionised hydrogen (the red stuff) and so looks black. This wispy string of dust lies about 5000 light-years away from the Earth, in the direction of Sagittarius, and is around 7 light-years long. There is also a pretty nice blue reflection nebula nearby.


NGC 6559

Cool dust illuminated by hydrogen light. NGC 6559 is about 7 light years across and 5000 light years distant. CREDIT: Gemini Observatory

Posted in astro blog by Stuart on Monday 29th Aug 2005 (01:20 UTC) | Permalink

Supernova in NGC 1559

The European Southern Observatory's (ESO) Very Large Telescope (VLT), in northern Chile, takes some amazing pictures. Here is a one taken on the 6th August 2005 showing the barred-spiral galaxy NGC 1559. This galaxy is about seven times smaller than our galaxy - the Milky Way - and is about 50 million light years away in the southern constellation of Reticulum (near the Large Magellanic Cloud).

NGC 1559 with SN2005DF
Spiral galaxy NGC 1559 showing SN2005DF. Image taken by the ESO's Very Large Telescope. CREDIT: ESO/VLT
Click on the picture above for the full-sized ESO version. The image was taken as part of a target-of-opportunity observation to catch a new supernova named 2005DF which I've labelled for you. The supernova had been found two days earlier by an amateur astronomer based in Australia, so the VLT was mobilised to observe it too. Astronomy is one of the few areas of science where amateurs can make new discoveries.

Posted in astro blog by Stuart on Sunday 28th Aug 2005 (10:09 UTC) | Permalink

Nicholson Crater

Nicholson Crater
A perspective view showing the central part of Nicholson Crater, Mars CREDIT: ESA/DLR/FU Berlin (G. Neukum)
With Mars Reconnaissance Orbiter (MRO) on its way to Mars, I thought I would post an image from the little red planet. This image was taken with ESA's Mars Express spacecraft during orbit 1104. It shows the central part of Nicholson Crater which is almost exactly on the martian equator at 195.5° East - it sits at the southern end of the Amazonis Planitia. The image was taken with the HRSC instrument and is a perspective view - there are also views from directly above and one from a different angle to give you a better view of the crater edge (very top of the image) and the central mountain.

Posted in astro blog by Stuart on Saturday 27th Aug 2005 (15:59 UTC) | Permalink

Hubble Law

I often read about galaxies, quasars and other such distant things in the Universe. When I say distant I really do mean distant; they are millions to billions of lightyears away from us. Not only are they far, far away (curse George Lucas for making that sound clichéd), but most galaxies seem to be heading off as if our galaxy had a really bad case of body odour. The first hints of this came around 1912 when Vesto Slipher first measured the velocity of the Andromeda Nebula (now known as the Andromeda Galaxy). Unfortunately, galaxies don't come with handy speedometers, so Slipher had to make use of a technique called spectroscopy to work out their speeds.

Every chemical element in the Universe gives off specific colours of light, from the colours you see in a rainbow to radio waves, UV rays and X-rays. These are called emission lines. In fact, each chemical has its own unique set of emission lines which allow us to tell it apart from all the rest. This gives astronomers evidence equivalent to fingerprints used by the police to identify criminals. So measuring the light lets us work out the chemical composition of distant objects, but it can do much more. When the distant galaxy is moving, with respect to us on the Earth, all the colours are changed in a nice, predictable way. If the galaxy is moving away from us they get redder (redshifted) and if it is moving towards us they get bluer (blueshifted). This change in the colour is called the Doppler effect after the Austrian scientist Christian Doppler. You've most likely heard this effect with sound waves as a police car speeds by you. It is also used by police radar to work out that you were driving at 37 m.p.h in a 30 zone.

So Vesto Slipher was able to measure the colours of the emission lines and work out how fast a galaxy was moving by how much redder or bluer it was than would be expected. He determined that the Andromeda galaxy was coming towards us rather quickly - about 300 km/s. This seemed a tad fast, so he checked the value by observing the Sombrero galaxy. That was even worse; it was moving at 1000 km/s away from us! Over the following years he measured the velocities of another 24 galaxies and was puzzled to find that all but four were moving away.

This remained a puzzle until several years later and a lot of work by Milton Humason and Edwin Hubble. Between them they measured the distances and redshifts of 46 galaxies and plotted the values on a graph (you can do this yourself). The graph showed that there was a definite link between redshift and distance; generally the further the galaxy from us, the more redshifted it was. This became known as the Hubble Law and we now know that it is due to the expansion of the Universe.

So for really huge distances, that would otherwise have way too many zeros on the end of them, astronomers tend to use the redshift value as a measure of the distance. Redshifts are usually represented by the letter 'z' and start at zero for something that isn't moving. The redshift increases as the distance increases, but this isn't linear so it quickly gets quite big. A distance of 5 billion light years corresponds to a redshift of about 0.5, 10 billion light years is about 2.0 and 13 billion light years is around 8.0. This can be confusing, so luckily Ned Wright at UCLA has created a cosmological calculator to help work it out.

The direct link between speed and distance has done a fairly good job for the last 80 years or so, but in the last decade observations of distant supernove show that it doesn't quite work at the very largest distances. That, as they say, is a story for another day.

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Posted in astro blog by Stuart on Thursday 25th Aug 2005 (14:51 UTC) | Permalink

Aurora Alert

AuroraWatch, run by the Space Plasma Environment and Radio Science at Lancaster University have issued two alerts about possible activity (Northern/Southern lights) within the last five hours. The first was an amber alert and the second, issued at 12.01 BST, was classed as "VERY HIGH local activity, possible ongoing geomagnetic storm". The real-time graph shows a lot of activity. The planetary k-index is up to 9. This may be linked to the M-class flares of Monday from sunspot 798. If is dark where you are right now, get outside and have a look for some aurora. I wish it wasn't the middle of the day here.

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Posted in astro blog by Stuart on Wednesday 24th Aug 2005 (13:23 UTC) | Permalink

Martian Hillwalking

The view from the Spirit Mars Rover as it climbs Husband Hill. CREDIT: NASA/JPL/Texas A&M
The Mars rovers are still going strong. The above image shows the view looking backwards as the Spirit rover closes on the summit of Husband Hill on Sol 581. You can just make out the solar panels in the bottom right and you should be able to see a couple of dust devils on the horizon. Husband Hill has two summits - Summit 1 and Summit 2 - and the rover team chose to visit the first. They initially thought Summit 1 was smaller, but now that they are almost at the top, they realise that it is higher. On 17th August Spirit was only six vertical metres below the summit, so there should be great panoramas of the view from the top, soon.

Steve Squyres - principal investigator for the Mars Rover mission - has a good Mission webpage which gives lots of detailed information about what each rover has been doing.

Posted in astro blog by Stuart on Monday 22nd Aug 2005 (24:00 UTC) | Permalink

Canadian Expo


Having mentioned Australia's Science Week, I should perhaps give a brief mention of the Canadian Space Agency who are taking part in Expo Québec. Although the Expo is already under way, there will be more presentations about astronomy next Friday, Saturday and Sunday in the Jules Verne pavilion. Entry prices (en Français) depend on age.

Posted in astro blog by Stuart on Sunday 21st Aug 2005 (10:57 UTC) | Permalink

Science Week Podcasts

This week has been science week in Australia. There have been many events across Australia which I didn't attend due to a minor problem of about 17,000 km or so. Instead, I've been listening to various science shows produced by the Australian Broadcasting Corporation (ABC) and podcast via the Internet.

Dr Karl's phone-in science show, broadcast on Triple j, is good fun and this week they talk about the physics of Space Shuttle re-entry and the possibility of astronauts passing wind in space. Radio National's Science Show podcast has an interesting item, by the editor of Scientific American, discussing the past and future of the US 'Star Wars' defence system. Although not Australian (except once), I don't want Slacker Astronomy to feel left out. They have a sound seeing tour of a Perseid spotting trip near Boston.

Here in the UK, the British Association (BA) will have its annual Festival of Science in Dublin from 3-10 September. Looking ahead, the next UK National Science Week will be 10-19 March 2006.

Posted in astro blog by Stuart on Saturday 20th Aug 2005 (10:19 UTC) | Permalink

From missiles to galaxies

Many years ago the radio dish, shown in the picture below, was used to track missiles at the Woomera Missile Range in Australia. The missile range was set up in 1947 (around the time that Jodrell Bank was set up) as a place to try out Britain and Australia's weapons systems. The first Skylark rocket was launched there in 1957, a few months before the USSR launched Sputnik. Of course the site had all the things you would associate with a space programme such as launchpads and tracking dishes but it also had its own theatre and even a song.

7m telescope
The 7-m telescope at Jodrell Bank Observatory with the 42-ft and Lovell telescopes in the background. CREDIT: Stuart
Around twenty years ago - in the mid 1980s - some of the tracking dishes were going to be scrapped. Through some international links, astronomers at Jodrell Bank were able to get two of these dishes delivered to the UK to be used for astronomy. One was named the 42-ft telescope and the other the 7-m. Actually, the 7-m telescope is not 7 metres but 6.4 metres in diameter. It got the name because of a rather poor conversion from feet to metres, although as this didn't result in the loss of a spacecraft it doesn't matter too much.

These days, the 7-m telescope is used by both undergraduate students at the University of Manchester and students undertaking Jodrell Bank's distance learning course in radio astronomy. It is a nice little dish that gets used to look at the Sun, map the spiral arms of the Milky Way and measure the mass of galaxies like M31 and M33. I think it is amazing to be able to measure how much hydrogen there is in an entire galaxy from the middle of Cheshire.

The 42-ft telescope, sitting next to the entrance of the main observatory building (you can just see it peeking out from behind the 7-m in the picture), now spends almost all its time monitoring pulsars. If the Crab Nebula is above the horizon, chances are that the 42-ft will be observing it as a pulsar lies at the centre. Pulsars usually emit two beams of radio waves and as they spin, these beams can sweep past us giving a 'tick' at the radio telescope. The ticks from the Crab pulsar have been recorded for many years, so an extremely precise value for the rotation rate is now known - it is currently 29.7808515419 +/- 0.0000000001 Hertz in case you were wondering. Even the slow down of the rotation has been carefully measured and occasional glitches - thought to be due to re-arrangements in the pulsar surface - are sometimes seen.

The two dishes have travelled a long way (quite literally) and are still doing lots of useful scientific research.

Posted in astro blog by Stuart on Friday 19th Aug 2005 (19:50 UTC) | Permalink

Orange Moon

Orange Moon
A rather orange looking Moon taken on 17th August 2005 CREDIT: Stuart
So much for green cheese. Last night, just a couple of days short of full moon, the Moon was hanging serenely over the houses that I see from my bedroom window. It was looking decidedly orange.

The Moon isn't actually orange, or made of green cheese for that matter, but sometimes it can look so. The reason is the Earth, or rather the Earth's atmosphere. Imagine you were stood on the Moon looking towards the Sun. Obviously, I don't advise that you normally look directly at the Sun, but this is our imagination so go with it.

At full moon, the Moon is almost on the opposite site of the Earth to the Sun although not quite all lined up. That means that to get to the Moon, light from the Sun has to skim through our atmosphere. It has to go through a lot of atmosphere and, for the same reason that sunsets look reddy-orange, the light which gets to the Moon is slightly orange tinged; some of the blue part of the spectrum has been filtered out by Earth's atmosphere. [Edit 20/8/2005] The light has to come back, through a lot of atmosphere, to your eye. It is this last trip which will do the rest of the reddening. That way, the amount of reddening will depend on your local pollution levels - different countries will see different colours. The Moon should also get less red as it gets higher above the horizon as there is less atmosphere for the light to travel through.

Posted in astro blog by Stuart on Thursday 18th Aug 2005 (14:01 UTC) | Permalink

First podcast from space?


This week, the BBC World Service's Go Digital podcast contains a segment discussing what NASA have termed the first ever podcast from space. It was recorded by astronaut Steve Robinson while on board the Space Shuttle Discovery in orbit around the Earth. Steve talks about the mission and his experience removing those pesky gap-fillers. What is really interesting - apart from what Steve says of course - are the background noises which you normally miss on the usual crackly transmissions. If you don't have speakers you can always read the transcript, but it just isn't the same.

However, Go Digital's Bill Thomson doesn't think it qualifies as a podcast with there being no RSS feed. I say that if it sounds like a podcast, can be (manually) put on your MP3 player like a podcast and Steve Robinson says it's a podcast that is good enough for me. Still, I echo Bill Thomson's statement that it would be great to see, or rather hear, more of these. A weekly round-up from the ISS perhaps?

Posted in astro blog by Stuart on Tuesday 16th Aug 2005 (20:27 UTC) | Permalink

Star camps


UK dark sky map

Stay away from the light! A dark sky map of the UK. CREDIT: Kielder Forest Star Camp
As autumn and winter appear on the distant horizon, it is time to start planning some observing for the longer nights. Observing doesn't have to be a lonely affair; you can be sociable and attend a star party. Your local astronomical society is always a good first port of call to find out about star parties in your area. However, if you feel like venturing further afield, there are a few star camps that are open to all.

The Loughton Astronomical Society and the Society for Popular Astronomy will be hosting the Autumn Equinox Sky Camp from Thursday 29th September to Sunday 2nd October. This year it is being held at Kelling Heath, on the northern coast of Norfolk, which is supposed to have a limiting magnitude of around 5.5. There will be talks, trade stands, an 'astroboot' and of course a chance to see the sky from a dark site - weather permitting.

If you live in the very north of England or the south of Scotland Norfolk may be too far to travel, especially as you have dark skies closer to home. If so, why not go to the Kielder Forest Star Camp on 10th September? They will also have talks and trade stands.

If you are interested in astronomy and want to do something during the day, you could attend the Society for Popular Astronomy's 2005 Convention. It is being held at the Institute of Astronomy, Cambridge on Saturday 15th October. Admission is free but there is limited space in the lecture theatre so make sure that you book ahead.

Posted in astro blog by Stuart on Sunday 14th Aug 2005 (11:21 UTC) | Permalink

Perseid Peak

The peak of the Perseid meteor shower should be occurring right about now (within an hour or so). Unfortunately for people in Europe and North America, it is currently daylight so I shall have to wait until later to have a look myself.

Perseid Meteor Shower
An illustration of the Perseid meteor shower showing the radiant. This would be the view at about 11 pm BST on 11th or 12th August CREDIT: Stuart/Stellarium
This week has been very cloudy here in Manchester, so I've not seen anything in the night sky. Weather folklore around these parts says that if there is enough blue sky to make a pair of sailor's trousers before lunchtime, the evening will be clear. I don't know how much blue sky that actually is, but earlier there was a patch of blue sky and it certainly has cleared up.

If you are in the UK and would like to go meteor spotting, you should go out into your garden - or any dark spot - during twilight and get yourself comfortable on a deckchair or sun-lounger looking towards the north-east. A blanket/warm jacket and a flask of tea or glass of wine may be useful too.

Try to find a 'w-shaped' constellation (Cassiopeia - the Princess) and look a bit below it towards the constellation of Perseus (the Hero). That is the direction that the meteors will appear to come from. The best way to observe them is to look, by eye, about 50 degrees away from the top of Perseus. Eyes are much better than a pair of binoculars of you have a wider view.

It should hopefully be a fantastic firework show.

Posted in astro blog by Stuart on Friday 12th Aug 2005 (17:17 UTC) | Permalink

ABC doesn't add up

The ABC science news is usually quite good, but I just got very confused over a story they have about the size of spiral galaxies. The article describes research recently published in the Astrophysical Journal (ApJ) which makes use of Gemini South telescope based in Chile. There is a pre-print of the paper at the arXiv if you want to read it for yourself. The researchers studied the density of stars as they moved outwards from the middle of a nearby (6 million light years away) spiral galaxy named NGC 300. They were looking for an obvious break in the density but were unable to find one - it was just a smooth exponential decrease. This implies that spiral galaxies could be bigger than currently thought.

What confused me were the last few sentences:

Bland-Hawthorn says the findings also have other implications for astronomy. "It has big consequences for the early universe," he says. NGC 300 has a high redshift, he says, which means we are seeing it as it was early in the universe."We are suggesting the galaxies in the early universe were also very big."And given the universe was an even more violent place in its youth, this makes the question of how large flat disc galaxies form even more of a mystery.


According to the NASA Extragalactic Database (NED), and indeed the published paper, NGC 300 is quite near and has a tiny redshift of 0.00048 (accuracy to the last decimal place). So, the last few sentences about it having a high redshift, and thus we would be seeing it early in the Universe (which is 13.7 billion years old), don't make much sense to me. The quote doesn't feature in the original Gemini press release though so I'm guessing the reporter had a horrific accident with cut and paste.

Posted in astro blog by Stuart on Thursday 11th Aug 2005 (11:05 UTC) | Permalink

IAU XXVI

Every three years, the International Astronomical Union (IAU) has a general assembly. This lets astronomers from all over the world get together to discuss the important astronomical matters of the day. I managed to attend the assembly in 2000 as it took place in Manchester - the travel/accommodation costs are minimal when you can use a bicycle from home. In 2003 it was in Sydney and next year, the 26th assembly, will be in Prague. Preliminary registration is already open and there are quite a few people signed up. I would really like to go to this one so I shall have to sort out some funding from somewhere.

Top of the preliminary registration list is a certain podcaster who either didn't pay attention to the input fields on the form or just wanted to use his first name to put him at the top of the list.

Posted in astro blog by Stuart on Thursday 11th Aug 2005 (10:09 UTC) | Permalink

Mars Reconnaissance Orbiter

The Mars Reconnaissance Orbiter (MRO) is scheduled for launch in just under three hours time at 07:50 EDT. It will take about seven months to get to Mars, finally arriving in March 2006. However, it then spends a further six months aerobraking process where it uses the top of the Martian atmosphere to help adjust its orbit. In November 2006 it will then start doing some proper science such as using radar to look below the surface (like MARSIS) and it will be taking higher resolution images than the Mars Surveyor spacecraft.

Mars Reconnaissance Orbiter
Artist Tina DiCiccos image highlights four important stages of the Mars Reconnaissance Orbiter mission: launch, aerobraking, science and relay. CREDIT: NASA/JPL/DiCicco
The images MRO sends back should have a resolution of around 1 metre, so will help to find boulder free landing sites for future landers. This will also allow it to look for Beagle 2 - possibly the first British spacecraft to get to Mars. As Beagle 2 never sent back a signal, nobody knows if it crashed or 'bounced' off the atmosphere during descent. Hopefully MRO will spot it.

Another goal of MRO is to act as an interplanetary relay for other Mars missions - it will sit in orbit around Mars transmitting back to the Earth. I think I read that it will transmit at Ka band which is around 30 GHz (or 1cm wavelength). NASA have moved up to a higher frequency as it allows more data to be sent. Hmmm ... I wonder what the strength of the signal will be.

Posted in astro blog by Stuart on Thursday 11th Aug 2005 (09:05 UTC) | Permalink

Cosmic TV

Let's start at the beginning. Well not quite the beginning, as that gets into the realm of philosophy and religion, but say a short time after the big bang. Space was very compact and as time went on it stretched. Quite quickly too. Still, with only a limited amount of space for all the matter in the Universe, things were a bit hot and crowded. It was so hot that atoms like hydrogen, oxygen, lead and the rest were unable to exist. Instead, the constituent parts - the electrons and protons - were spread all over the place as a sea of plasma.

Now, photons of light don't get too far in a dense plasma because they keep stopping to interact with the charged particles. This meant that the Universe was more opaque than a sheet of lead. However, space was still expanding and things were cooling down - allowing the first atoms to form as the Universe reached a temperature about the same as the Sun's surface. Once the electrons and protons had joined together to make electrically neutral atoms, about 300,000 years after the big bang, the photons were free to head off on their own.

Noise on a TV set

The CMB makes up a percent or so of the white noise on my TV set.


That light, from 13.7 billion years ago, has been stretched as the Universe has continued to expand - in much the same way as pictures on balloons get stretched as they are inflated. When the wavelength of light gets stretched, the amount of energy it has is reduced. Those very high energy photons from the year 300,000 are now in the less energetic, microwave, part of the electromagnetic spectrum. They were first accidentally observed by Arno Penzias and Robert Wilson of Bell Labs in 1965 using a microwave antenna in New Jersey although their existence had been suggested by people like George Gamow. The microwaves could be seen coming from every direction in the sky and the name Cosmic Microwave Background (CMB) was coined. The CMB is now extremely cold - it has a temperature of about 2.727 Kelvin (minus 270.425 degrees Celcius or minus 454.765 degrees Farenheit).

In recent years there have been a whole host of space, balloon and ground based instruments doing amazingly precise measurements of the tiny fluctuations in that temperature from one point on the sky to another. Although these are all very expensive, you don't need lots of money to detect the CMB. You just need a TV set.

Just tune your TV set between channels so that you see the 'snow' or white noise. This noise is mainly due to the components in your TV set which is at a temperature of about 300 Kelvin (room temperature). However, about one percent or so of that noise is actually due to microwaves from the Cosmic Microwave Background. Now that is cool.

Posted in astro blog by Stuart on Wednesday 10th Aug 2005 (16:11 UTC) | Permalink

Landed Safely

The Space Shuttle Discovery successfully landed at Edwards Air Force Base at around 13:12 BST after slowing down from 27,360km/hr to zero. No doubt a lot of people are very relieved.

Posted in astro blog by Stuart on Tuesday 09th Aug 2005 (14:05 UTC) | Permalink

Pesky Time Zones

Time zones cause no end of confusion when you have to go from one to another. There are plenty of time converters out there on the Internet but, if you are in the middle of reading something, you don't want to go off elsewhere. So I made a little bit of JavaScript so that I could display times in whatever timezone I liked and let everyone see it in their own.

It makes use of the title attribute of HTML tags to display the time in the visitor's local time zone (actually the time zone of their computer but they are likely to be in the same place). I also use a little bit of CSS to add a small clock symbol, to the time, in the same way that Wikipedia does with external links.

The script should be fairly forgiving - it can allow 'am', 'a.m.', 'pm', 'p.m.' between the time and the time zone. It should also cover most one, three or four letter time zone abbreviations. It will return the local time in as similar a format to the one you used as it can e.g. with/without a leading zero, with/without minutes. Here are some examples for you to put your mouse over: 02:34 am ACDT, 9 am CEDT, 18 EDT, 20:09 BST, 5 pm UTC, 07:29 HAT. If you find any mistakes in the code, please let me know.

Quick HOWTO:

Download the JavaScript file and include it at the top of the HTML document body using:

<script language="JavaScript" type="text/javascript" src="timeconverter.js" />

You may want to add the following CSS in your style file (download the image):

dfn.time {
background: url("timeconverter.png") center right no-repeat;
padding-right: 13px;
}


Now you can display the time using something like:

<dfn class="time" onmouseover="UTC(this)">05:43 CDT</dfn>

Posted in astro blog by Stuart on Monday 08th Aug 2005 (19:57 UTC) | Permalink

Five Live goes astro

What on Earth is going on? Are BBC Five Live having an astronomy day or something? Yesterday I spotted that the folks at Slacker Astronomy will be on Five Live early on Tuesday morning (quoted as 01:50 GMT) and now, thanks to Ian, I see that The Bad Astronomer will also be on Five Live tonight just afterwards at 6:00 pm PDT (although as Phil Plait thinks this is 2 am UTC, it could be an hour later or earlier). I've also just discovered that Dr Karl (of ABC fame) has a phone in on Five Live. These are all streamed live over the Internet and available for up to seven days from transmission.

As ever, to avoid confusion over what time these are for you, hover your mouse over the times to get them translated to your local time zone. I wish other people would make use of my bit of JavaScript as it would stop me getting timezone headaches.

Posted in astro blog by Stuart on Monday 08th Aug 2005 (17:09 UTC) | Permalink

Faint fuzzy

On Saturday the weather cheered up a bit from the cloud and rain of the last few weeks. That allowed me to go outside and have a look at some stars. I still don't have a telescope of my own and at the moment there is no access to the one at the university due to building work. So, I was left with just my trusty digital camera to take some shots of the sky.

The area of Manchester that I live in has lots of rows of terraced houses and the view from my backyard looks very similar to that in the opening credits of the British soap opera Cornonation Street. Despite the limited horizon that this gives, I can see the summer triangle from my back door.

Looking around towards the east/south-east, at 11pm, I spotted the square of Pegasus. Taking the top left corner of the square (if you live in the northern hemisphere) you can then follow two curved lines of stars leading up towards Cassiopeia. These two lines make up the constellation of Andromeda (the Princess) who, in mythology, was the daughter of Cassiopeia (the Queen) and Cepheus (the King). Using the stars in Andromeda you can look for the Andromeda Galaxy which is the furthest thing you are likely to see with the unaided eye at a distance of almost three million light years.

However this is Manchester, so the light pollution stopped me from seeing it without a pair of (borrowed) binoculars. Below is a picture that I took with my digital camera. I have processed it to remove all the large scale structure (the orange sky glow) so that it doesn't look quite so orange! Depending on the contrast of your monitor, you can just about make out a little smudge where M31 is supposed to be. You may need to clean your monitor if it is as dusty as mine! It isn't as good as the night sky shots of Tom or Ian, but not bad for my digital camera in the middle of Manchester.

M31 in Andromeda
Part of the constellation Andromeda showing the Andromeda Galaxy (M31). Taken with a Fuji Finepix S602Z on 6th August 2005. CREDIT: Stuart

Posted in astro blog by Stuart on Monday 08th Aug 2005 (16:05 UTC) | Permalink

New Server

If anyone has tried to post a comment over the last few days you will have found that you were unable to. That is because I decided to move the entire website to a new server and didn't want to lose any interesting comments in the process. The new server is run by someone I know, so I have real support if I need it.

Unfortunately, the CommentSpam™ people seemed to realise that the new site was working before I did, so the RSS comment feed was filled up with junk (and one real message). The spammers don't seem to stop even though I keep coming up with new ways to counteract them. If it continues, I think I may have to implement a real person check before allowing comments to be posted. This may ask an easy, astronomy related question along the lines of 'What is the fourth planet from the Sun?'. I would have to make sure that the questions are quite easy though. Perhaps they would be based on the post that people were adding a comment about. My only worry is that this would make things difficult for people with English as a second language. Does anyone have any good ideas or solutions?

Posted in astro blog by Stuart on Monday 08th Aug 2005 (16:00 UTC) | Permalink

Perseids!

Meteors often get called shooting stars, although they don't really have anything to do with stars. They are actually grains of rock, floating around in the Solar System, that happen to get too close to the Earth. As they plummet through the atmosphere, they burn up and create glowing trails through the sky that last for a second or so. If you sit outside on a clear dark night, watching the skies, you should probably see the odd meteor or two. They are really cool to spot although you can't really point them out to your friends as they are too fast. At certain times of the year, however, you can see whole showers of them. Meteor showers occur when the Earth smashes through the trail of debris left by a comet as it orbits the Sun. We know the Earth's orbit and those of quite a few comets very well, so the timing of these showers is easy to predict.
On the nights of the 11th and 12th of August, say from about 10 pm BST, you should stand a good chance of seeing the Perseid meteor shower. The Perseid meteors were shed from the Comet Swift-Tuttle, at some point in the past, and appear to come from a point (called the radiant) in the constellation of Perseus. When they hit the atmosphere, they will be travelling at a fairly fast 60 kilometres per second. If you live in Europe, North America, Russia, Japan (or anywhere else at about the same latitude) the map below should give you an idea where to look. It is probably best to look about 50 degrees away from the radiant - the point where all the white lines seem to be coming from.

Perseid Meteor Shower
An illustration of the Perseid meteor shower showing the radiant. This would be the view at about 11 pm BST on 11th or 12th August. CREDIT: Stuart/Stellarium
While you're looking for the Perseids, why not have a look to see if you can spot Mars, near the horizon, in the East? Mars isn't at its closest, but it is still an impressive sight through a small telescope.

Posted in astro blog by Stuart on Thursday 04th Aug 2005 (14:42 UTC) | Permalink

Where is 2003 EL61?

For those of you that want to know where to find 2003 EL61, it is currently in the constellation of Coma Berenices. It has a magnitude of 17.2 which is about 29 million times fainter than Sirius. Below is a map that Megan made using Xephem. The positions were calculated using orbital elements from the Minor Planet Electronic Circulars. You can get them yourself for 2003 EL61 and 2005 FY9.

Sky map of 2003 EL61 and 2005 FY9
A map created to show the locations of Kuiper belt objects 2003 EL61 and 2005 FY9
CREDIT: XEphem/Megan

Posted in astro blog by Stuart on Wednesday 03rd Aug 2005 (16:21 UTC) | Permalink

A name for 2003 UB313

The discoverers of 2003 UB313 have sent a name to the International Astronomical Union (IAU) for approval. Of course, that doesn't mean it will be chosen, but the discoverers managed to successfully suggest Sedna a couple of years ago. Mike Brown (quite rightly) refuses to state the name they have submitted, but he does give clues.

He says that Kuiper belt objects are normally named after some figure in a creation mythology. Most of the existing planets are named after Greek/Roman gods, so that is a starting point. However, an awful lot of those names have been used up for comets/asteroids etc. and are in short supply. Mike says that in the past they have used native American, Inuit and minor Roman gods but they want to expand to different traditions (my emphasis).

So what culture/tradition might they use? Well, the discovery observations were done with the Gemini North telescope, so perhaps they thought they should honour the local traditions by picking a Hawaiian god. Here are some suggestions that may be suitable for a tiny, distant, cold planet:

  • Keawe: a spirit who lived in a vast, empty land, a dark abyss at the beginning of the world.
  • Milu: lord of the spirit world and lord of Ka-pa'a-he'o, where souls who had departed their sleeping or unconscious mortal body might end up if they were not pardoned by their 'aumakua (personal gods) during their wanderings
  • Maui: a demigod who fished the islands of Hawaii from the sea after a little mistake he made on a fishing trip
  • Fetu: (Samoa) god of the night
  • Hikuleo: god of the underworld
I think that Keawe seems the most apt. I don't think it is likely to be Xena, as suggested by the UK national press, as she is a fictional character. How many other planets are named after fictional characters? (Pluto the dog was named after the planet not the other way around). I should stress that these are my own personal thoughts so are no better guesses than anyone else's. If anyone else has any suggestions, add them below.

Posted in astro blog by Stuart on Tuesday 02nd Aug 2005 (13:37 UTC) | Permalink

Astrology for Plants

Moon behind Lovell The Sunday Times yesterday reported that Prince Charles farms according to the phase of the Moon.  Unfortunately, it seems that you need to register to read the story on their website, but you can hear what Prof. Heinz Wolff has to say on the matter in Radio 4's Broadcasting House, fast forward to about 38 minutes to hear his bit.  He points out that it might sound silly, but there may be something to it.  The Moon does have a measurable physical effect on the Earth (not just tides in the ocean, the land also has tides but they are less easy to measure), but how much of an effect this has on plants is debatable since there are many things in the environment that have much more of an effect.

Posted in astro blog by Megan on Monday 01st Aug 2005 (23:10 UTC) | Permalink
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