Flickr user FlintstoneStargazer captured all 110 of the Messier Objects between March 7th and August 6th this year. They have all been compiled into a big mosaic. This is very cool - anyone else ever tried anything like it?

Finally my paper studying the Ophiuchus star-forming region is done and dusted and has been accepted for publication. Thanks to one of my intrepid co-authors, that paper appeared today on astro-ph, the preprint paper listing for astronomy and astrophysical theses.

We re-analyse all of the archive observations of the Ophiuchus dark cloud L1688 that were carried out with the submillimetre common-user bolometer array (SCUBA) at the James Clerk Maxwell Telescope (JCMT). For the first time we put together all of the data that were taken of this cloud at different times to make a deeper map at 850 microns than has ever previously been published. Using this new, deeper map we extract the pre-stellar cores from the data. We use updated values for the distance to the cloud complex, and also for the internal temperatures of the pre-stellar cores to generate an updated core mass function (CMF). This updated CMF is consistent with previous results in so far as they went, but our deeper map gives an improved completeness limit of 0.1 Mo (0.16 Jy), which enables us to show that a turnover exists in the low-mass regime of the CMF. The L1688 CMF shows the same form as the stellar IMF and can be mapped onto the stellar IMF, showing that the IMF is determined at the prestellar core stage. We compare L1688 with the Orion star-forming region and find that the turnover in the L1688 CMF occurs at a mass roughly a factor of two lower than the CMF turnover in Orion. This suggests that the position of the CMF turnover may be a function of environment.

It is a study of star formation and prestellar cores, the objects that precede protostars. You can access the online abstract and get more information at arXiv.org or simply download the PDF from Orbiting Frog.

Telescope Limiting Magnitude = Visual Limiting Magnitude - 5*logd + 5*logD

, where d is the aperture of the human eye and D is the aperture of the telescope. So to give some examples, let’s consider a normal sky where the visual limit is around Mag 5.5 and you have a little 3-inch refractor telescope. We’ll use 3mm as the aperture of the human eye.

Telescope Limiting Magnitude = 5.5 - 5*log(0.003) + 5*log(0.07) = 12.3

So with a small refractor you can see down to a limit of about Mag 12. Pluto however is at Mag 13.8 so this would not suffice. Here is the maths for my own situation. Last night the sky was so dark I could make out Mag 7.0 stars, this is my visual limit and it is about right for very good observing conditions. The telescope I am using has a 9cm aperture.

Telescope Limiting Magnitude = 7.0 - 5*log(0.003) + 5*log(0.09) = 14.8

This puts Pluto into the realms of the feasible, which was great news since Pluto from my location is well above the horizon and unobscured by light pollution. Also, this week I have set myself the goal of observing all the planets, and Pluto - just for fun.

Pluto can currently be found in Sagittarius at the painfully dim magnitude of 13.8. Along with its sister body Charon and two satellites Nix and Hydra, it is a very cold, dark and far away place. Even the best images ever taken of Pluto reveal little more than a patchy ball of rock. I was unable to take a picture myself, far too dim, but Googling reveals a handful of amateurs have succeeded.

The image above is taken from Mauna Kea and the one below comes from an amateur named Bill Dirk.

If you want to try and see Pluto, I can now recommend a few things to help you along. Firstly, check that you have dark enough skies. This isn’t trivial, I have rarely had as good conditions as last night. Unless you have a very big telescope (more than 15cm) you’ll find Pluto is beyond your reach in anything other than exceptional skies.

Secondly, know where to look. Using the Meade with a good calibration means that getting into the general vicinity of Pluto is fairly easy. you need to know your stuff if you’re using a regular, manually guided telescope. Whatever happens, you need tracking, other wise the objects you find will vanish before you can see them at all.

Thirdly, get a good map of the planet’s location and memorize the patterns of stars around it. Once you’re looking at a star-field in the eyepiece, it will look the same as every other star field, unless you know what you’re after. Most planetarium software will give you this, the trick is figuring out the field of view you will be looking at through the eyepiece. I recommend using the 12DString FOV Calculator.

Finally, have patience. This will take time and several attempts. Even if you do find it, if you’re like me you’ll feel the need to verify everything twice anyway. But I think it was worth it!

Having finally seen Pluto I am now compelled to complete my planetary observation collection. All of the planets are visible during the night at some point from my current spot. I will not be here much longer so I need to get out and see them all. I have never yet seen Neptune or Uranus and I have only seen Mercury twice.

I’ll report back later in the week.

I am stuck and need some help in both taking and then processing the images. I know there are loads of photographic astronomers out there - I need you!

I’m using a Pentax digital SLR, which can perform exposures up to 30 seconds long. I don’t have fancy tripod but I do have a small, pocket tripod. Last night I tried out some different settings and ended up using either ISO 800 or 1600 speed and the full 30 seconds of exposure available to me.

I took, amongst other things, these three images. The first is the Plough, the second is the Summer triangle and the third is Jupiter, hanging nicely above the house.

What I need to know are what most people starting out would need to know I imagine: what are the best websites, tools and softwares packages that one should try to use when starting out? Do I need to be stacking these images to get the best results, if so how?

I have RAW image files for all of these, but what does that get me? Googling is a bit of nightmare, as all you really see are all the images everyone else has made - which are lovely (and intimidating) - but not useful in getting you there yourself.

All assistance much appreciated.

You may have noticed that I have ‘fallen off the internet’ this week, as a friend of mine recently said in a text message. Well the reason is that I have been attending a meeting about star formation and the Spitzer Space Telescope.

I am part of the Gould Belt Survey team working with Spitzer legacy data. Currently I am sat in a meeting but I thought I would post an entry explaining my absence from the web, which will actually continue for the next couple of weeks.

I may still posts the odd cool Digg story and the Abram’s Skynotes will continue. In the meantime, keep the emails coming in and watch out for the space station in the next few days. there are some more good sighting awaiting all of us.

Black holes are very interesting things, aren’t they? There’s something fascinating about those things which are so hard to understand. Black holes are one of the most asked about objects at almost any public space talk. Certainly school children seem to be obsessed with them!

So a question I was asked this week (by both John and Margaret) was ‘what is the smallest size of a black hole?’. If a star can collapse into a small space and become a black hole, can a planet or even a proton? Well yes, they can, so long as you squash them down hard enough.

There is no theoretical limit on the sizes of black holes. A black hole is determined by how much mass is being contained within a radius. If you put enough material inside a small enough space, you get an object which is so dense that even light cannot escape: a black hole.

Put another way, if you were to squash down any object far enough you eventually get a black hole. This critical size is called the Schwarzschild radius. For example, the Schwarzschild radius for the Sun would be 3km and for the Earth it would be about 9mm. Just imagine compressing the Earth down to just 18mm across!

The follow-up question from John was a great one:

Newton’s olde cannon fired objects toward the horizon at faster and faster speeds until they reached escape velocity and ‘fell’ into orbit. Fair enough, but this idea was never applied to light because light was just too damn fast and also no one believed it was affected by gravity anyway. Now we know better. So does this mean that if a beam of light approached a black hole at precisely the right glancing angle to match its speed that it would not fall in but form a kind of ‘light in orbit’… like saturns rings but made only of light?   

I had never though of this before - which is why I love people sending in questions. So I went to find out from some people who should know, here at the university, whether light could orbit a black hole. The answer surprised me: ‘yes’.

It turns out that light can orbit a black hole, but not for very long. Just beyond the event horizon of a black hole (the distance at which nothing can escape), there is a short distance in which an incident photon is deflected into a circular ‘photon orbit’. It won’t stay very long in this state though. These orbits are highly unstable and soon the photon would either spiral into the black hole’s event horizon or be ejected outward again. I just really like that this can happen, even it happens for a very short time. I wonder what it looks like?

I hope that this is just as interesting for everyone to learn about. If anyone out there knows more on this topic, I’d love to hear from you.

I’ve not much to say about this other than that it is a very cool image. I took it on Wednesday during Cardiff University’s Dragonfly Day. As well as making our own spectrometers there was also an experiment to deduce the contents of several mystery cups. All were white or see-through liquids. Using just their sense of smell and a UV blacklight, participants had to figure out what was inside each cup.

Just so you know, the contents were:

• A Suncream
• B Washing Power (for clothes)
• C Shampoo
• D Toothpaste
• E PVA Glue
• F Lemon Juice
• G Double Cream
• H Tonic Water
• I UV Sensitive Body Paint

Orbiting Frog has been growing and changing for as long as it has been around. Every now and again, it’s good to take stock and get some thoughts from people who read the blog. Now that there actually are people reading it, this process is much easier!

I’d like to hear your thoughts on the things you like and dislike about Orbiting Frog and any changes or modifications you’d like to see. This could include anything from the way the blog looks and feels to the topics covered or the regularity of updates.

Good, bad or ugly - don’t worry I can take it, although I will delete needless cruelty and profanity! Please leave your thoughts either in the comments below, via Twitter or via email.

So I thought maybe you’d all like to know a little about what this new litter has to offer, and who the runt is, if there is one.

What’s Up Astronomy (Alan Dyer)

This guy covers the bulk of practical, amateur astronomy. He discusses what you can see in the night sky; he talks about planetariums; and he takes some nice photographs. This is great, practical stuff and I have already subscribed. A bit like the astronomy column in a newspaper, the What’s Up blog fills that factual, observer niche that we all want to read about once in a while. Unless we’re cosmologists.

Space Across the Pond (Chris Lintott)

I like Chris’ style and so I generally enjoy his stuff regardless of topic. He also has the knack of writing for the internet: short, snappy and to the point. I wish I could always stick to that ethos.

Chris is described in his Discovery bio as covering astronomy “as seen from Europe”, which truthfully I find a bit odd. Yes there are lots of Americans in the world, but this is the internet. Also, isn’t the European perspective really quite similar to most others when it comes to space? Astronomy is a fairly international game. I don’t read the Mars Phoenix Twitter feed for the Martian perspective. Anyway, I’m nit-picking. The blog is good and the name hardly matters.

Twisted Physics (Jennifer Ouellette)

To clarify: Jennifer is said to have a black belt in jujitsu and live with “a tall cosmologist name Sean”, so I’m not going to be very mean here am I? The posts here are a little more in-depth and ‘feature’ like than most of the others. The authors writes very well and covers interesting and unusual topics. a bit like the sort of stuff Wired would cover. I could learn to like this blog and will keep an eye on it. Its not Digg material, which is a shame. But other than Bad Astronomy, very little thoughtful stuff seems allowed to get far on Digg.

Cosmic Ray (RayVillard)

Going back to titles (I really am a pedant) this one is a pun. How do I feel about puns? I LOVE them! Cosmic RAY… get it? Ray is director of news for the Hubble Space Telescope. I’m not sure what that means, but I had thought that it would produce a Hubble new bias on his blog. It doesn’t, and this is a good sign. The blog is very readable and I’ll have to read it for a bit to see if I like it.

Next Generation (David Chandler)

Not sure what to say about this one. It is described to new visitors as being about student astronomy, which made me keen to read it. I’m a student and thus it seemed like he would be talking about the kinds of things student astrophysicists and astronomers are up to. But whilst this is true, there are also non-student related posts thrown in. Not a problem in of itself but when you start to think that this is one of six blogs that are part of the same collective, you wonder whether it is overkill. However at least half of the posts present are student-related and these are very interesting. Check out the post about Caesar’s path to Britain as a good example.

Space Disco (Dave Mosher)

This blog is written by the same guy that, I think, is producing the whole lot. This makes me think of it as a sort of editorial. As such it is more personal and I guess the word is ‘fun’. It looks perhaps at lighter topics with titles like ‘Supernovae Taste like Stawberries‘. I like the style and the content of this one and so I have subscribed.

In general I would say that they are all well-written and professionally put together. These are journalistic blogs. Perhaps it is partly for this reason that I wish they were not all separate. What I’d really like to see - and this is my principle wish for this family of blogs - is that they all combine into one big website.

I’d like to see a main page elsewhere, perhaps at a root address of /space, which presents the latest posts from all the authors in a kind of online astronomy magazine. I want a combined RSS feed and therefore organised coverage to avoid overlapping stories. With all those great writers, covering that wide-range of topics, I would subscribe unfailingly. There would also be room for an irreverent UK PhD student in amongst the posts of that magazine, if you ask me (ahem!).

So in conclusion: go and read. Try these blogs out. Ultimately they will all speak for themselves over time. They look at the outset to be of a high quality and as such do well at raising the bar for astronomy blogs once again.

Spectrometers are used, like prisms, to spread light out into the component colours. This enables us to understand the compositions of everything from stars to streetlights. Here I show you how to make your own spectrometer and give you a few examples of what you can see with it.

What You Need:

• A cardboard tube (toilet roll or kitchen roll tubes are just perfect, in the pictures here, I have used more black card to make a tube myself.)
• 2 square pieces of black card (approx 8cm x 8cm)
• Black tape or masking tape (something that blocks out light)
• Razor blades (nothing fancy just cheap blades that are not attached to anything)
• A stanley knife
• An old CD

Make a Diffraction Grating:

Cut a small square hole (approx 1cm across) in the middle of one of your 8cm x 8cm black cards. Break the CD into pieces, just snap it. You’ll need a section of the broken CD that can nicely cover the 1cm hole in your card.

Using a bit of sticky tape, peel away any cover remaining on the piece of CD, so that it is transparent. Use tape to stick it over the hole, creating a sort of window. This will be our diffraction grating.

Make a Very Fine Slit:

Using a stanley knife, cut a slit in the middle of the other piece of 8cm x 8cm black card. This slit should be about 2cm long and just a few millimetres wide. Tape the the two razor blades either side of the slit. They should make an even narrower slit, just 1mm or less if possible!

The aim is create a very fine, narrow slit though which light can travel. Make sure the blades are securely attached with tape for safety.

Make the Spectrometer:

This is the easy bit! You now attach the two square cards to either end of the tube using the dark tape. You have to attach it in such a way that no light is let into the tube accidentally (hence the dark tape). When you look through the diffraction grating, you only want to see light coming from the slit.

Testing Out Your Spectrometer:

The best way to see how this works is to use daylight. Just point the spectrometer toward a window during the day or up at a cloud if you’re outside. You should not ever look directly at the Sun. You should see a nice, smooth spectrum (rainbow) somewhere in your field of view in the tube. Here is a photo of a cloud taken through my own spectrometer. The bright white light is the slit and spectrum is just off to one side.

What’s Happening?

When light enters the tube though the slit it spreads out - all waves do this when passing through small slits. The CD then makes the separate colours visisble to your eye. You see a nice, even spectrum from daylight sources because daylight is made up of all the colours of visible light from the Sun. Once you can see this pattern, you can start trying to find the spectra of other things.

In our physics lab we have lamps of different chemical make-ups. These let us see pure light from different sources. Here are a few I took today, all photos taken by my own camera through my own, homemade spectrometer.

Here is the spectrum for Zinc, which you can see contains some red and blue but very little green.

Cadmium is very distinctive, with short sections of each of the three primary colours and very little between them. It is less spread out than Zinc. There is a big gap between the green and red sections.

Krypton is seen to be fainter than the others here, but the spectrum is still visible. The blue section has become much more violet or indigo here and the green is greener than it was in Cadmium.

The Astronomy Connection:

This is how astronomers know what stars are made of. They use advanced spectrometers to measure the spectrum of stars and pull out the ‘fingerprint’ patterns of colour that you see above. Each element has a unique set of spectral lines (colours) and these can identify the presence of different chemicals in stars, nebulae and just about everything else.

This is the whole spectrum of the Sun. It is so detailed that it had to spread onto multiple lines to see it properly! You’ll see that in fact it is not perfectly evenly spread out as I suggested earlier. This was taken with a very advanced spectrometer that has a greatly increased sensitivity compared to one made here, but its based on the same principles.

Things to Look At With Your Spectrometer:

• Sodium streelights
• Compare daylight to a lightbulb.
• Different light bulbs look different (that’s why energy saving bulbs light up the room in a different way).
• Neon signs.
• TV  and computer screens.
• LEDs from computers or remote controls (these give very pure spectra, often only one colour).

Have fun with your spectrometer and why not try and take a photo through it? It worked fairly well for me. I’d love to see any photos you take with it, or of it. Let me know how you get on. Thanks to the Science Made Simple team for this great idea!

The problem is that the detector arrays for the device are currently at the NIST (National Institute of Standards and Technology) lab in Boulder, Colorado where a ‘radiation incident’ has taken place. Contamination from plutonium means that no one can enter the lab and the detectors are currently inside.

The incident is described on the NIST website, which says that “a small plutonium spill occurred on June 9″. The sample that is thought to have caused the leak would have contained just one-quarter of a gram of plutonium. This seemingly tiny portion of radioactive material was accidentally spread around by a lab worker who also used a sink to wash his hands while contaminated.

The lab has since been inspected and many surfaces are contaminated including “the floor [and] various tabletops and surfaces, consistent with a spread of material by hands and shoes”. NIST are working with experts and hope to have the situation resolved soon.

Meanwhile, SCUBA-2 has to wait. It has now been two weeks and as soon as the science team can get their hands on the arrays they hope to begin the next phase of work and try to bring to life a device which many have been waiting for with anticipation.

SCUBA-2, and its orbital cousin Herschel, will begin a new era for the science of star formation and submillimetre observing. You’ll hopefully be hearing a lot more about both these instruments right here in the weeks and months to come.

From The Planetary Society weblog: The place: the Podkamennaya (Lower Stony) Tunguska River in central Siberia, northeast of Lake Baikal; the time: 7:14 a.m. on the morning of June 30, 1908. Within minutes the “Tunguska Event,” the largest asteroid impact in modern recorded history, was over.

100 years ago today!

Read More.

There is a lot more to the universe than the light you and I can pick up with our eyes and brains. Although its a shame that we can’t see them naturally we can use technology to reveal the wavelengths of light normally invisible to us. Visible light is only part of the electromagnetic spectrum (a very small part) and I thought it would be interesting to see some familiar objects in unfamiliar ways.

The electromagnetic spectrum is usually split into seven parts: the radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray. You can find a good schematic of the EM spectrum over on Wikipedia. We obviously see things in the visible, but some creatures, such as bees, see some of the ultraviolet (one reason there are so many purple flowers). Here is a picture of a Geranium in the visible and then the UV. You can find more images like these, for all kinds of flowers over at this website.

But this is an astronomy blog and so here are some objects seen in multiple wavelengths. Some of them may surprise you. First up is the Moon. Here we have it in the radio, microwave, infrared, visible, ultraviolet and x-ray.

The infrared image (top right) shows various bright spots. These are warm areas on the Moon. The brightest spot, in the bottom-center of the Moon is the crater Tycho, which also shows up brightly in the visible and UV images. The X-Ray picture is from ROSAT (bottom-right). Here we see the Moon shown in its quarter phase to highlight that it is only reflecting X_Rays from the Sun and not giving any off itself. The Submillimetre (microwave) image (top-centre) was taken using the SCUBA camera on the JCMT in Hawaii. This is a camera normally used to image dust in nebulae and faint galaxies.

Next let’s look at something more exotic but still familiar, the Andromeda Galaxy. Also called M31, this is closest neighbouring galaxy in the wider universe and is just about visible from a good site. We are seeing this in the radio, microwave, infrared, visible, ultraviolet and x-ray.

You can really start to see now why observing objects in different wavelngths can tell us something about them that we didn’t know before. The different details in each image are coming from different parts of the galaxy. In the top-center image, which is taken at 175 micrometres, we are seeing the dust lanes between stars in the galaxy. The X-Ray image in the bottom-right shows us only the extremely energetic objects, which as we can see, are located predominantly toward the centre.

Another easy to spot object, which you may know of is M45, also known as the Pleiades or Subaru. Once again here it in the radio, microwave, infrared, visible, ultraviolet and x-ray.

The most impressive image here in my opinion is the X-Ray image from ROSAT (bottom-right). It looks to me like something from Doctor Who. It is also interesting to note that M45 doesn’t show up as much in radio frequencies. In the top-centre image we can see only some of the stars. This is because M45 is a young cluster and some of the surrounding dust still obscures the stars in this far-infrared image.

I thought I’d save the best til last: here is the Earth. Now its tricky to get pictures of our own planet - because we’re on it. We’re lacking in any good radio images of the Earth because you can do radio astronomy perfectly well without putting telescopes in space. However I really like these images because they really took me by surprise. In order, these images show the Earth in infrared, visible, ultraviolet, extreme-ultraviolet, x-ray and gamma rays.

The first image shows the infrared emission on the Earth from water vapour. Like the two UV images, this picture is from an extensive network of Earth-observing satellites that are attempting to investigate how our planet operates. Tectonics, oceanography and climate change are just three of the many topics being studied to ever-more depth by NASA, ESA and researchers the world over. The X-Ray image (bottom-centre) shows an aurora on the Earth’s north pole. Other than this high-energy interaction between the atmosphere and the Sun, the Earth seems to be invisible at this wavelength.

Finally we have the gamma ray image (bottom-right). What you’re seeing here are extremely high-energy particles, mostly from outer space, reflecting off the Earth’s atmosphere. The edge of the globe is seen to be much brighter than the center because cosmic rays hit the atmosphere at a shallow angle and are more likely to create detections. There is an imbalance btween the East and West due to the Earth’s magnetic field, which is asymmetrical.

I hope you’ve enjoyed this little collection, if you know of any other cool multiple wavelength images - astronomical and otherwise - then please leave a comment with a link.

You can also buy a similar design on a t-shirt from the Orbiting Frog Shop. Available in sizes for women, men and kids in many colours. Prices start at $18 (£9) for kids and $20 (£10) for adults, international delivery available. There is the design you see above and also a black and white, vertical option.

Thanks to JPSmythe I have been playing with Wordle, a website that creates graphical representations of documents. Above you can see my paper on star formation in the Rho Ophiuchi region as a Wordle cloud. Below is the same document in the original LaTex format. anyone that knows the joys of LaTex will understand what all those odd words are.

I also wordled the recently influential WMAP paper, which studied the cosmic microwave background in great details:

Hubble’s famous paper on the expansion of the Universe and the nature of red shift:

Then I thought to query the astrophysical papers database for the most cited papers to see what names or keywords came up. The results can be seen here:

I also thought it would be interesting to do the popular Bad Astronomy blog (current RSS feed):

Finally here is the current word cloud for Digg Space:

PS: Can you tell I am a little bored today?

August 1st 2008 will see a solar eclipse visible across much of Asia, Europe, the Middle East and some portions of North America. Maximum totality is seen in Siberia, but you can also see the Moon totally obscure the Sun in many parts of China (and the North Pole if you’re about). The eclipse is often being called the 2008 Olympic Eclipse because it comes just days before the commencement of the Summer Olympics in Beijing.

In other parts of the Old World, a partial eclipse will be seen. The regions covered by partial eclipse are seen in the above diagram outlined in light blue, with totality in dark blue. If you want to know the details of what can be seen in your area, then I’d use the very handy Google Map provided by NASA.

This map allows you to double-click anywhere and find the start, maximum and end times for the eclipse that is visible in your locality. For example, in Cardiff the eclipse begins at 0930 (BST) and ends an hour and a half later.  You are also told the eclipse magnitude, which is basically a measure of how much of the Sun’s face, the Moon will cover. In Cardiff this will be around 21%.

Check out the site for info on your own area and if you plan to watch the eclipse, don’t forget to either project the Sun’s image onto a piece of paper, or order a set of eclipse viewing glasses.

This amazing image was taken using an extremely fast, advanced technology. A short burst of laser light, mere attoseconds long is seen here, weaving its way through the electromagnetic field. Out of this world!

Read More on New Scientist

The white stuff on Mars sublimated, meaning it can’t be salt and pretty much must be ice. Congrats to the Mars Phoenix team (and whoever picked their landing site). Surely this goes down as one of the best animated GIFs for many years.

These images were acquired by NASA’s Phoenix Mars Lander’s Surface Stereo Imager on the 21st and 25th days of the mission, or Sols 20 and 24 (June 15 and 18, 2008). 

These images show sublimation of ice in the trench informally called “Dodo-Goldilocks” over the course of four days. In the lower left corner, lumps disappear, similar to the process of evaporation. 

Mars Phoenix Press Release.

I found out today that I have annoyed some of my gravity-wave-studying contemporaries with My Beef with Gravity Waves. It got me thinking about gravity waves again and about black holes. I found a website, black-holes.org which has some interesting stuff. One highlight I thought I’d share are the sounds of black holes and other gravitational events.

Gravity waves, like any wave, can be interpreted as sounds and when they are, you get some interesting combinations of clicks and tones. Here are a few of the most interesting ones. Apparently they were all created by Teviet Creighton.

To begin we have the sound of a nice, steady object: a pulsar. These rapidly spinning, neutron stars produce gravity waves with a nice, regular tone. One day, I hope someone creates a gravity-wave telescope/instrument combination using pulsars as the keys.

Download audio file (periodic.mp3)

Two black holes that meet will merge and coalesce into a single, larger black hole. Here’s the sound of just such an event, where each black hole is about ten times as massive as the Sun.

Download audio file (inspiral.mp3)

An extreme mass-ratio binary is a system where two objects orbit each other, but one is far bigger than the other. This type of system is very well understood and takes a long time to evolve and infall. This next sound is that of an extreme mass-ratio black hole binary as it collapses…

Download audio file (extremebh.mp3)

and here is the same kind of event, but with more lead in time. This lets you hear the gradual change of the pitch and the ‘knocking’, as the black holes are drawn slowly closer together.

Download audio file (extremebh2.mp3)

The brightest events in the universe are supernovae: the death of giant stars. This cosmic flash is very different when observed through the microphone of gravity waves. Here is a supernova, blipping out of existence:

Download audio file (supernova.mp3)

Another familar idea seen through an unfamiliar, gravitational lens is that ’sound’ of the early universe. The Big Bang left a kind of echo, which was also represented by a gravtational background noise. If you had been detecting gravity waves during the early life of the universe it would have sounded like white noise.

Download audio file (earlyuniverse.mp3)

Finally, what is actually heard by a gravitational wave detector? They are not yet powerful enough to actually have made any detections because of noise. Like trying to see faint stars with all the street lights on, gravity wave detection suffers the problem of the Earth and its associated tremors. Earthquakes, lorries, even people create quakes and shakes which are confusing to gravity wave detectors. The microphone on a gravity wave detector would actually not hear the crisp tones so far discussed, but would actually hear this:

Download audio file (microphone.mp3)

There’s more to be found on the black holes website, and there will be more here on Orbiting Frog on the matter of gravity waves as soon as I collect my thoughts and actually get some work done!

Pareidolia is something that Phil often covers on Bad Astronomy. It is a term describing the seeing or hearing of things that seems significant where there is actually nothing. Whilst browsing the excellent Worth1000 archives, I came across this image of someone that looks just like Phil! The competition title: pareidolia. Who’s have thought?

I mean, I think it looks like Phil, but maybe I’m just imagining it…

Worth1000.com | Photoshop Contests | Pareidolia

GLAST has now launched after a few delays in the last couple of weeks. But no worries! Soon the £350 million mission between NASA and the US Department of Energy will begin showing us the gamma-ray sky. GLAST will orbit about 350 miles above the Earth has a five year mission to undertake. For more info, there is a good BBC News article and also the official GLAST website.

You learn more about Planck and the LFI and HFI instruments via this link and you can also follow the craft’s Twitter feed. I like this whole Twittering spacecraft thing - its so accessible and easy for anyone. Brilliant.

Oh and did I mention that Cardiff University is heavily involved in Planck, particularly with the HFI instrument which was built here.

What you will need:

• A regular drinks can
• A pot of cold water big enough to submerge the can
• A pair of tongs
• A kitchen hob (gas or electric is fine).

What to do:

Now you have to be careful with this one. The tongs have to be good or you’ll burn yourself. If you’re a child reading this, then make sure someone supervises you while doing this experiment. Reading though all the instructions before you start out is vital. I recommend having a couple of attempts, so maybe have two or three cans ready. So let’s begin:

Whilst you are filling up the pot of water why not drink the coke or whatever is in your drinks can. We don’t need any of the contents for this experiment, just an empty can. Once it is empty, rinse it out and place about two tablespoons of water in the can.

Now take your tongs and get a firm hold on the can. Hold it over the kitchen hob. We need to boil the small amount of water we have put in the can. This won’t take long and you’ll know when it’s worked because you’ll see steam coming out of the hole at the top of the can. Let it steam for a minute or two to be sure the water has all boiled.

Now here’s the cool bit. Keeping the can in between the tongs, take the can directly from the hob and dunk it, upside down, into the pot of water. The can will instantly and violently be crushed! It will happen very quickly so be ready. When I did it, it made a loud smacking sound as it went under water. I did it twice because I missed it the first time!

What is happening?

There is some great physics going on in this simple experiment. When you heat up the can and boil the water inside, the can fills with steam and pushes out all the air. Then when you dunk the can into cold water, the steam quickly condenses into water and there is no air pressure inside the can to support it. The can cannot resist the forces pushing on all sides from the water and air above it. Therefore it is crushed instantly!

Balloons:

Air pressure is also at work in balloons. When you blow air into a balloon you are artificially increasing the air pressure inside it and the rubber skin expands outward, forced by the force of the air molecules bounding around inside it.

You can ‘crush’ balloons by dipping them into liquid nitrogen. This condenses the air inside into a liquid and the balloon goes flat as a pancake. Here can see a video of a balloon that has been dunked into liquid nitrogen thawing out. The air boils back into a liquid and the balloon re-inflates. We filmed this last year in our first year undergrad physics lab.

Enjoy playing with air pressure and feel free to send me any images of your crushed cans!

Universe Awareness for Young Children - Kenya

We were just chatting in coffee and the topic of ‘light bulb’ jokes came up (along with some serious dubious jokes involving snowmen). Here are some astronomy examples of the staple ‘light bulb’ joke. Please add any more in the comments.

Q. How many physicists does it take to change a light bulb?
A. Eleven. One to do it and ten to co-author the paper.

Q. How many astronomers does it take to change a light bulb?
A. None, astronomers prefer the dark.

Q. How many radio astronomers does it take to change a light bulb?
A. None. They are not interested in that short wave stuff.

Q. How many general relativists does it take to change a light bulb?
A. Two. One holds the bulb, while the other rotates the universe.

Q. How many science fiction writers does it take to change a light bulb?
A. Two, but it’s actually the same person doing it. He went back in time and met himself in the doorway and then the first one sat on the other one’s shoulder so that they were able to reach it. Then a major time paradox occurred and the entire room, light bulb, changer and all was blown out of existence.

Q. How many infra-red astronomers does it take to change a lightbulb?
A. Two, one to change it, and one to bang on about the one they once changed while they were at the VLT.

I just wanted to reiterate that it is really worth taking a look, and there is a great site produced by the team that not only uses the Google Maps interface (.astronomy!) but also highlights some features like nebulae to help the uninitiated viewer.

Take a look!

Here’s a cool new design from the Orbiting Frog Shop. It’s a t-shirt which shows a puzzle. The aim is to identify the 24 silhouetted space-related objects. It has been a while since I featured anything from the Orbiting Frog Shop, but with the recent spate of posts I thought was time once again to show what you could be wearing around the planet.

This design is available in a wide range of sizes and colours for grown ups and kids alike. Prices start at $17.99 for kids t-shirts and from $19.99 for adults. Items can be delivered worldwide and delivery times are excellent, even outside the USA.

Oh, and just in case you were wondering, the answers are printed on the bottom of the front of the t-shirt upside down. This way they can easily be read by the wearer of the item but not so easily by everyone else.

The paper that caused this trouble describes how LIGO has been used to place a low-limit on some properties of the Crab Nebula pulsar (you can read it here if you like). The way this paper was announced at the AAS meeting in St. Louis made it sound like they had a detection. But they didn’t and don’t (yet). Interestingly, I wasn’t all that excited though. For a few moments I was quite convinced they had finally made a detection and although it would have been historic I could only think of one thing: so what now?

The scientific community has been thinking about gravity waves for a very long time. They are a part of general relativity - although they were conceived of before that. To the non-astronomer, they basically answer the question, ‘what would happen if the Sun suddenly vanished?’. Would the Earth instantly fall out of orbit or wold it take time? Would we see it happened before or after we felt it happen?

The answer is that gravity is ‘transmitted’ via waves and that it travels at the speed of light - so we’d see and feel it at the same time. Gravity is thought to propagate through spacetime, much as light propogates through the electromagnetic field. The ripples it creates in spacetime are very tiny though and so they are extremely hard to detect.

So if you could ’see’ gravitationally energetic events, then what would you do? Well it would allow you to perform a new kind of astronomy. It would open a new spectrum of analysis and viewing on the universe. This new spectrum would range from highly energetic events (e.g. coalescing black holes) to lower energy events (e.g. accretion disks). Mainly it it interesting in the way it would let us look into the physics of black holes.

Huge amounts of money have been ploughed into gravity wave physics. Interestingly the gravity waves groups around the UK always seem to have a lot of money! They use it to meet up and discuss theoretical results. They create lavish PR campaigns and recruit PhD students. They take data with LIGO and its contemporaries. What they do not do, and have not yet ever done, is detect a single gravity wave!

I realise this is political, but it always irks me slightly. Gravity waves have lots of money but no results. ESA is potentially going to bump another project in favour of contributing to LISA, a gravitational wave detector in space.

So I am asking for anyone that knows something about gravity waves to give me some reasons to like the idea of studying them again. I used to when I was a kid. They are very cool, they are high-tech, but they are  - for now - undetected and very, very expensive.

So any general relativity enthusiasts/experts out there who can offer me something to work with? Anyone?

This HiRISE image shows a 10km crater on the northern polar plains of Mars, called Heimdal. This isn’t the point though. The bright spot highlighted is the Phoenix lander descending to the surface. This incredible picture was captured on May 25th by the HiRISE camera onboard the Mars Reconnaissance Orbiter. The orbiter was 760 kilometers away from Phoenix when picture was taken.

This has to be one of the most incredible images taken in 2008. It says so much about what is going on in space exploration at the moment. If Phoenix finds what it is looking for, namely evidence of water ice and habitability, then this image will become truly iconic.

This image also came in just minutes after the event took place and spread virally throughout the internet within hours. The world is interested in what is happening on Mars. As a race, we seem to be captivated by our neighbouring planet. It seems to have taken control of our ambitions. Manned missions and more probes will cement this obsession in the coming decade(s).

To be able to image one craft from another proves that we have created reliable, durable methods for exploring other worlds. The longevity of NASA’s martian rovers and the new, larger version of this mission heading to Mars next year (Mars Science Laboratory) have created a tangible, real perspective on the planet. It no longer seems so alien. Of course it is when people set foot there that we will feel as if we are truly capable of great things again.

It may well be that what we are discovering on Mars is something we are in short supply of at the moment here on Earth: optimism for the future.