Archives For exoplanets

Yesterday was the Hack Day at the UK National Astronomy Meeting 2014 in Portsmouth. I organised it with my good friend Arfon Smith of GitHub, formerly Zooniverse. We wanted to try and start a new NAM tradition – it went well so maybe we did. I’m psyched that .Astronomy got to help make it happen – not just through my involvement, but the many .Astronomy alumni who attended!
Some of the hack projects have already started to appear online, such as Geert Barentsen, Jeremy Harwood, and Leigh Smith (Hertfordshire) who created a Martian Nyan Cat, which is planning to fly over the entirety of ESA’s Mars Express data archive in one continuous, two-day-long, flight. You also grab the code for Duncan Forgan’s beautiful ‘Music of the Spheres’ project, which sonifies the rhythms of planetary systems. Other projects are harder to place online, such as Jane Greaves’ knitted galaxy cluster – with dark matter contributed by many people during the hack day itself.

I spent much of the day working with Edward Gomez (LCOGT) on the littleBits Space Kit. littleBits is a modular system of circuits that let anyone try their hand at something that ordinarily requires a soldering iron. littleBits components may be switches, sensors, servos, or anything really, and they connect magnetically to create deceptively simple circuits that can be quite powerful.


For example you could connect an infrared sensor and an LED to make a device that flashes when you press buttons on your remote. Or you could use a microphone and a digital LCD display to create a sound meter. The littleBits components are sturdy enough to withstand being bashed about a bit, and simple, and large enough, to let you stick on cardboard, homemade figures, or anything else you find around the house. I found out about littleBits when I met their creator, Aya Bdier at TED in March. She is a fellow TED Fellow.

We decided fairly quickly to try and built an exoplanet simulator of some sort and ended up crating the littleBits Exoplanet Detector (and cup orrery). There were two parts to this: a cup-based orrery, and a transit detector.

The cup orrery consisted of a rotating ‘planetary system’ fashioned from a coffee cup mounted on a simple motor component – we only had hack day supplies to play with – and a central LED ‘star’. Some more cups and stirrers were required to scaffold the system into a stable state but it was soon working.

The transit detector used a light-sensor component that read out to both a speaker and a LCD numerical display – Ed refers to this as the laser display board. With a bit of shielding from the buffet’s handy, black, plastic plates the light sensor can easily pick up the LED and you can see the light intensity readout varying as the the paper planet passes in front of the star. It was awesome. We got very excited when it actually worked!

You might think that was geeky enough, but it gets better. I realised I could use my iPhone 5s – which has a high-frame-rate video mode – to record the model working in slow motion and allow us to better see the digital readout. We also realised that the littleBits speaker component can accept an audio jack and so could use the phone to feed in a pure tone, which made it much easier to hear the pulsing dips of the transits.

Finally, we had the idea to record this nice, tonal sound output from the detector and create waveforms to see if we could recover any properties about the exoplanets. And sure enough: we can! We built several different coffee-cup planetary systems (including a big planet, small planet, and twin planets) and their different properties are visible in their waveforms. Ed is planning a more rigorous exploration of this at a later date, but you can see and hear the large cup planet’s waveform below.

Waveform for Large Cup Planet

Waveform for Large Cup Planet

So if you want to try something like this, you only need the littleBits Space Kit. You can buy them online and I’d love to see more of these kits, and to see them in schools. I’m now totally addicted to the idea myself too!

GitHub Stickers

Thanks to Arfon for suggesting that we do this Hack Day together; to the NAM 2014 Portsmouth team for being so supportive; and to GitHub for sponsoring it – where else would we have gotten all the cups?!


We recently posted news of a Planet Hunters planet discovered as part of a seven-planet system. Like all the Planet Hunters stars this is one seen in data from NASA’s Kepler spacecraft. Dubbed Kepler-90 this system is a peculiar microcosm of our own Solar System, with small (probably rocky) worlds in the middle, and larger (probably gaseous) worlds on the outside. The major different being that the outermost planet in this system is as far from the star as Earth is from the Sun. The other six planets in this system were already known about, but thanks to volunteers on Planet Hunters ( we now think that there are seven worlds circling this stars, which is just a little brighter than our Sun.

New PH Planet

To celebrate this fact I have created a model of the whole planetary system in Celestia, an awesome, cross-platform, open-source package that lets you explore space. You can download the Celestia files model directly here or watch the video below to be taken on a tour of Kepler-90 and it’s seven worlds.

In this video, I’ve given the newly discovered Planet Hunters candidate some fetching green rings – which we do not have any evidence for or against. Also keep in mind that we know very little about what most exoplanets look like, so we’ve used artistic license to give them all different appearances, often using the surface of what might be analogue worlds in our Solar System. Maybe you can spot some familiar surfaces amongst them!

This system has some great features that make it interesting. The outermost world is roughly the the size of Jupiter but orbits at almost exactly the Earth-Sun distance of 1AU. A Jupiter-like world in an Earth-like orbit has been seen before in Planet Hunters discoveries. The middle planet in this system is at the same distance from this star as Mercury is from our Sun, but is six times as large. The rest of the planets whizz around in even smaller orbits. This star is a little hotter than our Sun so they are pretty scorching places with surfaces temperatures in the hundreds of degrees – nearly a thousand for the innermost planets.

Inner System of KOI-351

The two innermost planets are roughly Earth sized and are really cool. The innermost one is 1.02x the diameter of Earth and the next is 1.18x. We assume that they are both rocky since they are so small. They orbit the star in just 7 days and 9 days respectively and are very close together. So close in fact that if you’re living on the inner, smaller planet then every few weeks, for about a week, the second planet appears in the sky about half the size of our full Moon.

Every year I see the rumour going round that Mars is going to be as big as the full moon. It will never happen for us – but on the tiny worlds circling Kepler-90, it happens all the time.

Update: The system used to be called KOI-351 but was given the name Kepler-90 just a day after this post went live. I have updated the name of the system in the text.

[Cross-posted on the Planet Hunters blog]

Image Credit: Jack Newton

Image Credit: Jack Newton

There’s a cool paper on arXiv today in which an intrepid band of astronomers (I assume they were/are intrepid) search for exoplanets around the stars in the Pleiades using Subaru. Spoiler alert: they don’t find any! However, it’s an interesting look at how to hunt for planets and small/faint objects in general.

They find 13 potential planet candidates around 9 stars. 5 of these were confirmed as background stars and two more are dismissed because they either didn’t appear in all data or the data that did appear in wasn’t good enough. Two more were found to be known brown dwarves, with masses 60x the size of Jupiter. The remaining 4 candidates still await further data to confirm their motion across the sky – but aren’t though to be planets either.

By not detecting any planets with a very sensitive instrument they are able to estimate an upper-limit for the frequency of such planets around stars in the Pleiades. So by not finding planets, they learn something really interesting. Well done, science.