Monthly Archives: February 2010

I am Moonpie, destroyer of worlds

As I type, there is presently an interesting little web application running through the world of twitter. This is My Solar System 2.0. It is a simulation of orbital mechanics for 2-4 bodies, allowing users to place these bodies in such a way as to create solar systems. One of the bodies could be a moon, another a star, perhaps the last two ordinary planets. You can define the initial positions, velocities and masses of the objects involved and if you want hints on where to get started – there’s a few situations (including gravitational slingshot, four star ballet and binary system with planet) already preset in the drop down menu to the right.

I got a link to this from @SheldonCooper, a twitter account associated with the Big Bang Theory character whose granny calls him Moon-pie. I retweeted this in the hope of providing @David_Kipping a game he can play whilst allegedly doing something tangentially related to his own work (using photometric and spectral data to determine the orbits of exoplanets). But it was picked up by @astroengine (Dr Ian O’Neil of Discovery News) and from him @plutokiller (Mike Brown of Caltech, whose discovery of large Kuiper belt objects gave impetus to the reclassification of Pluto). So now half the world’s scientific twitterati is presently playing with what is actually quite a standard teaching aid.

The simulation is from the stable of the University of Colorado at Boulder. I’m pretty sure if you look through all their various interactive simulations, you’ll find one or two from your childhood if you’re of a certain age. One in particular caught my eye, that old familiar natural selection one that involves setting an initial number of rabbits and introducing wolves and disease in order to set a stable and hopefully healthy population that doesn’t overeat. I remember using telnet to get that from the university severs in the earliest part of the nineties, just before the new thing of web browsers made it a bit easier.

There are of course lots more physics ones to play with, including John Travoltage, which I haven’t looked into…


In a pickle about spectra?

After seeing a tweet by Jim Wild (who tweets here), I found out about the ‘electric pickle’ teaching method. Astronomers talk about spectra a lot – how everything emits light with a fingerprint of colours assigned to them – but it is sometimes hard for people to conceptualise how, for example, sodium in one state is going to react the same way to sodium in another.

The lecturer in the following clip has already taught his students the mathematics of why this is so, but he has tacked on a little practical demonstration. He begins with sodium lights, showing the familiar yellow glow of a neglected town, moves on to spray salt water into the flame of a blow torch, to show that too glows yellow from the thermal energy imparted, then pulls out his pickle.

Dill pickles are notoriously salty and if you pass a current through them, the energy imparted will again cause the sodium to glow the familiar yellow. This is demonstrated here:

This one is brighter, but a little less scientific:

Solar Stormwatch

The latest exhibit in the Zooniverse (which tweets here), which sprang from the Galaxy Zoo (which tweets here) citizen science project, has been launched.

Solar StormWatch (which tweets here) takes data from the twin STEREO spacecraft that watch the Sun. These spacecraft produce three dimensional images of the turbulence on the solar surface. I remember a few years ago Chris Davis mentioning his group had been sponsored to design instruments, build them and retrieve data from them (in this case the Heliospheric Imager), but no funding was available to analyse what came back. Instead, the Rutherford Appleton Laboratory dumped the data onto a server and invited other scientists to do with it as they will.

Now the same solution has been reapplied with a little Galaxy Zoo magic to produce something ordinary people can be a part of. Users of the website are invited to examine data on explosions on the solar surface and track outbursts as they head toward Earth. This will allow scientists to be alerted to incoming disturbed conditions that may lead to damage to unshielded electronics, disruption to communication and auroral effects. There’s a bit of ‘spot training’ and then you’re off classifying solar disturbances.

As we’re at the start of a solar cycle, it is pretty quiet up there (see for example), but getting noisier. As the project progresses and more people join, there will be more to see and more discoveries for other users to confirm.

Oh, and they also have a nice gallery on Flickr of auroral events.

STS-130 lands with a bang and a flash

Well, two bangs – the twin sonic booms from Endeavour’s hull as it came in to land – and a flash from a fire in an Auxiliary Power Unit exhaust. The shuttle has three APUs used to control hydraulics during powered ascent, reentry and landing, but they can function fine with just one running. The APUs pump and ignite hydrazine to provide energy boosts and that stuttering roaring sound that accompanies the shuttle coming down. On rare occasions, the atmospheric conditions are such that the exhaust is visible as a yellow flame. This has been observed before. Here’s a video of the STS-130 landing from NASA’s Youtube Channel:

The most famous case of an actual APU fire was the ill fated shuttle Columbia that made a perfect landing following STS-9. STS-9 deployed the European in space experiment pallet, SpaceLab 1 back in 1983. It came back to Earth after a computer problem or two and when the orbiter was examined post launch, it was discovered a hydrazine fire had occurred and burnt itself out following a leak in two APUs, creating quite a bit of damage. Nothing was apparent so far as views of the landing from the outside were concerned as you can see from ABC’s coverage at the time:

But there were some actual fireworks as Endeavour went down. As with everything that enters the atmosphere, the shuttle heated up. Looking down from the International Space Station, JAXA‘s ISS expedition 22/23 astronaut Soichi Noguchi tweeted an image he took of reentry.

STS-130 and the Eye in the Sky

Tonight at around 00:54 GMT, the space shuttle Endeavour on mission STS-130 will depart from the International Space Station and they will drift apart in preparation for Endeavour’s landing, planned for the Kennedy Space Center in a couple of day’s time. The mission timeline can be seen here.

STS-130 began with the final ever night planned launch of a shuttle. Endeavour sailed into the night (after a few failed attempts) taking the Tranquility module with it.

The shuttle then approached the ISS and performed a backflip, allowing the station’s high definition cameras to scan the heat shields for any signs of wear and tear there may have been following launch. The two space platforms then came together and docked.

The mission has seen work to fix Tranquility to Unity and configure the cupola that will give residents of the ISS a new view on the world.

They gave interviews to the media and took phonecalls.

…and now they have said their goodbyes and will prepare for the journey home:

That journey will be broadcast on NASA TV and if you visit Heavens Above and check when the ISS is supposed to be visible above your location, the first fly overs after separation will show two travelling stars – the shuttle and the space station still close together in the sky.

The media here have been closely following the mission. A British born astronaut, Dr Nicholas Patrick, was launched with Endeavour and participated in space walks. The cupola and its view on the world held the attention for a while and then it was revealed Japanese astronaut Soichi Noguchi (who tweets here) has been tweeting pictures from space, making use of the new data connection that has for the first time allowed direct broadband internet access from space. Previously, they were on the equivalent of a dial-up connection as there wasn’t a deal to provide coverage to something flying over all parts of the Earth. As there are official things to upload and download from the ISS, this restricted what else could be done with the data channel. Even tweets had to be emailed down and then uploaded to an account by a technician on the ground. Now it can all be done directly.

In space, they can now hear you tweet.

Sun Dog no longer there

As the rocket carrying the Solar Dynamics Observatory launched towards space, two atmospheric effects came together to give the crowd below an interesting show.

Sunlight refracting through ice crystals in the air created an effect called a Sun dog, whereby a cloud was lit up in a spectrum of colours (I thought that was a separate effect, an iridescent cloud, whereas a sun dog is a bright point created by the coming together of several arcs, but anyway).

The rocket breaking the local speed of sound at that layer of the atmosphere created a shock wave that rippled out from it. This is a more normal effect, but what happened next was videoed (see from the 1:50 point onwards, it is repeated twice thereafter).

Some astronomy software

A recent tweet alerted me to an enormous list of astronomy software (freeware, shareware and demo, so no cost, but some may have use restrictions such as a time, functionality or copyright limits on the results). There’s 750 programs on the list, but it is intended to move up to a thousand as soon as possible. Naturally, on a list this size, there’s a couple of broken links, but don’t let that put you off. The list goes from simple widgets to tell you when the next new Moon is to complex data processing and observatory control algorithms. Something for everyone.

It’s here.