Lurking Giant

Well this is quite interesting. There’s some latest news about the possibility of a giant planet lurking on the outskirts of our solar system. The near mythological “planet X” which astronomers have been hunting for for decades. This latest study come from Konstantin Batygin and Mike Brown, and I must say, their actual work seems a lot more cautious than many of the news headlines being thrown about. But that’s no shock. So let’s break this down, because it’s really quite interesting.

People have been hunting for planets beyond Neptune for a long time. Neptune was officially discovered in 1821, after it was noticed that Uranus had some perturbations in its orbit. The theory was that a previously unknown large planet was tugging on it gravitationally. Neptune was found to be the culprit, validating the hypothesis. But Neptune also has perturbations in its orbit, and so planet hunters continued their toil, eventually confirming the existence of Pluto in 1930. Pluto, however, is too small to have much effect on something the size of Neptune. The hunt continued awhile for the so-called Planet X♠︎ until the idea eventually fell from favour. Turns out, after more closely examining Neptune, it behaves exactly as it’s supposed to. But there are still a few things unaccounted for in the outer solar system.

Sedna‘s ludicrously eccentric orbit, for instance, can only be explained feasibly in 3 ways. It was captured from somewhere outside the solar system, it was yanked into a bizarre orbit by a passing star, or it was flung out that way by a large planet. Even if it’s simply that Sedna’s adopted, there are other unexplained phenomena in the mix.

All alone in the dark

The idea is not new. The wraithworld which was discussed in 2011 met with some staunch opposition, for instance. But Batygin and Brown are actually rather cautious in their paper (which is freely downloadable if you’d like to take a look yourself). They aren’t claiming the existence of any such planet, but simply presenting a hypothesis. Their ideas all seem perfectly sound to me.

I'm quite fond of eccentric things. Can't imagine why...One of the things which their hypothesis aims to explain is the orbits of several highly eccentric solar system objects. Notably, these objects all have a perihelion (the point at which they’re closest to the Sun) at a very similar distance. This clustering of perihelia is quite unlikely, with only a 0.007% likelihood of having happened by chance. No good scientist likes to explain things away with coincidences. Even if Sedna is adopted, it wouldn’t explain this.

Some detailed modelling suggests that this, together with a few other features of Kuiper belt objects, can be explained by the presence of a large planet in a highly eccentric distant orbit. “Large” in this case, means about 10 Earth masses, though a planet as small as 5 Earth masses may suffice. Perhaps our solar system does have a super-Earth planet in it after all. So that’s nice. Overall the hypothesis is consistent with observations, explains a number of different phenomena by only postulating a single entity, and fits with existing knowledge. A rather promising hypothesis then. There’s more info directly available from Mike Brown himself, who will no doubt do a much better job of explaining it than I would.

So the only thing remaining to prove this hypothesis is to find the smoking gun – if this planet exists, no one knows where it is, though we know roughly where to look. I have my suspicions that if it’s out there, we’ve probably already seen it in one or more of the many sky surveys that astronomers are constantly doing. Unfortunately, given how slowly it would appear to move at such a huge orbital radius, we may not have realised what it was and not known what we were seeing♣︎. An obvious thought is to search for it by looking for stars which move between the different survey dates. But all stars and other objects move. Some of them quite fast. It’s going to be a long search, probably with many more computer simulations to work out all of the details.

Actually, it’s quite likely that Neptune was first spotted by Galileo in 1612, who didn’t realise that he was looking at a planet. It was seemingly in the background of some of the sketches he made while his attention was focussed on Jupiter.

♠︎ That was originally a roman numeral, by the way. Planet X = Planet number 10.

♣︎ Just like Galileo.

Image credits:
Upper – Artists impression created by myself. Starfield background freely downloaded under a CC0 license.
Lower – ©2016, The American Astronomical Society. Taken from figure 2 of Batygin & Brown (2016) and reproduced here in accordance with fair use policies for the purposes of research, criticism, review, and news reporting.

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❝ Our doubts are traitors,
and make us lose the good we oft might win,
by fearing to attempt. ❞

William Shakespeare, Measure for Measure

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How to write a proposal – part II

A few months ago, I wrote a little about how to put together a research proposal. At the time, I acknowledged that I was no expert and had a lot still to learn. I still acknowledge this, perhaps now even more so. Winning grants is a pretty big part of how science works in our modern world, and so I forsee my learning on this subject to be ongoing for a long time. If I’m good enough to succeed in my chosen career path, I expect it will be ongoing indefinitely.

This post offers no advice itself. It’s a collection of links to articles written by people far more experienced than myself. Standing on the shoulders of giants, as they say.

This isn’t even all the pages I found, but it seemed like a nice collection of them. Needless to say, I’m not the only person trying to claw my way to the top of this. If you’re reading this, maybe you’re in a similar boat.

Now… I have some more reading to do…

Proposal writing and rainy days...

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“She is an astronomer”

Today marks the 100th anniversary of women being allowed membership into the Royal Astronomical Society (RAS) in the UK. While this is most certainly a thing to celebrate, one thing about this still gives me pause. It’s only been 100 years.

100 years is not a very long time in one of the world’s oldest fields of study, in which we routinely talk about billions of years as if that were nothing at all. I find this to be another reminder that some of the people who I consider to be personal heroes would not have been able to join the RAS when they were making their discoveries. Back then, women were indeed rejected from membership purely because of their gender. The fact that they persevered should be a source of great admiration. The optimist in me wonders if the work which these scientists tenaciously undertook may have been one of the deciding factors, while the pessimist in me wonders how much further we could be if societies like these hadn’t closed out half the human population for so long.

A very close friend of mine recently said something which feels relevant here. She told me that she sometimes felt like she wasn’t proud of her achievements for their own sake, but because she made them while being a woman. The idea of this upset her, and she’s definitely not the only one. The sad thing is that often, certain people are noted for their achievements not because of their inherent merit, but because they made those achievements while not being white middle-class men.

Quicquid Nitet Notandum

The RAS is one of the world’s highest profile astronomical societies, and the driving force behind one of the largest scientific journals in astronomy – the Monthly Notices of the Royal Astronomical Society (or MNRAS for short). Before it was a journal, it was actually the society’s newsletter. It’s no longer monthly, no longer contains notices, and is now open to researchers from anywhere in the world, but I guess they thought the title was quaint. Originally founded as the Astronomical Society of London in 1820. Of course in those rather more misogynistic times, astronomy was a pursuit considered purely for “gentlemen,” despite the many contributions of women. Needless to say, astronomy wasn’t the only field in which this was true.

Mind you, it’s quite interesting to realise that the RAS allowed women membership in 1916, when you consider that women in the UK weren’t even allowed to vote at the time. Women over the age of 30 who met “certain property qualifications” were given the right to vote two years later in 1918 – a right which wouldn’t be extended to all women over 21 for another 10 years.

In light of this week’s latest sexual harrassment turmoils in astronomy, this seems to be a poigniant reminder. For over half of its existence, the RAS was a boys club. This is thankfully no longer true, but the fact remains that very often women are treated as second class in science (and elsewhere). To some extent, this may still be a hangover from the misogynistic origins of modern science. This needs to be fixed. We should be better than that by now. I was angry about this before and I’m still angry now. We’re improving, but we have a long way to go.

I don’t wish to dampen this celebration, by any means. The fact that our society now is less bigoted and segregated is definitely a thing to be celebrated. But be careful to which message you listen. The @RAS_Outreach twitter feed has been celebrating women in astronomy all day. It’s inspiring. But remember to give them respect as scientists in their own right, and not just as “women who are scientists.” And consider what good role models they’ll be for all those little girls out there who aspire to work in STEM fields when they grow up. Find out more about them, and tell your daughter/niece/little sister/cousin all about it.

Stars in science

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Comic by Hannah Blumenreich. Happy Caturday!

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An item on my wish list: See a sunrise from orbit.

Sunrise from Orbit

Earth’s atmosphere scatters out the blue from sunlight. The scattered light makes the atmosphere look blue, but the sunlight has all of its blue photons scattered out from it, giving it that distinctive sunset orange colour. It’s somehow even more apparent when seen from space like this. Billions of molecules scattering trillions of photons lighting up Earth’s atmosphere like a jewel in the night as you pass out from behind the planet’s shadow.


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Winter Wonderland

A few days ago, the Cassini spacecraft, 1.61 billion kilometres away in orbit around Saturn, made its closest ever pass of Saturn’s tiny moon Enceladus. It flew by around 49 km above Enceladus’ south pole – perilously close by astronomical standards. For comparison, Felix Baumgartner‘s record breaking skydive was from 39 km above Earth’s surface.

The objective of Cassini’s daredevil stunt was to take a close look at the watery plumes being ejected by the tiny moon to try and work out what drives them. And to gain some insight on the extent of Enceladus’ expected subsurface ocean.

While it was passing by though, Cassini also snapped this closeup image of the little planet’s surface…

Actually, the surface gravity on Enceladus is only 0.113 m/s² (compared with Earth's 9.807 m/s²). So you could probably jump over those bumps and ridges a bit like Super Mario...

What you’re seeing here (after image correction to fix the blurring – that craft was going extremely fast) is the wrinkled surface of the icy little world. The white scale bar is 1 km on this scale. Which means that all of those ridges are about the same size as streets and roads we may be more familiar with. To be honest, this part of Enceladus looks like a terrible place to go hiking.

While this may be the closest image of the surface we’ve ever seen, it’s by no means the only one. In case you’re curious about what it might be like to visit this tiny iceworld, here are a few others…

Give it a couple of hundred years, and I’d be very surprised if no one’s opened a skiing resort on Enceladus…

All images: NASA/JPL-Caltech/Space Science Institute.

I have to agree with @TychoGirl – The Khumbu icefall looks comparatively inviting!

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Painted leaves

Sunset on Mars

Ladies and gentlemen and variations thereupon, I’d like to introduce you to Chrissy Sparks, – who creates some really quite marvellous space art, which she sells in her store on Etsy. You can also get a slightly more behind-the-scenes look via her instagram feed. Her necklaces are gorgeous, but I’m really a huge fan of the painted leaves she makes. When I eventually get an office of my own, this is the kind of thing which I’ll probably use to decorate my walls…


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This is a completely gratutous Saturn system appreciation post. Because Saturn.

Images found courtesy of

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Postcards from Pluto

New Horizons passed Pluto some time ago, but it’s still slowly dripping data back to us. The tiny craft wasn’t optimised for data transfer, so its hard drives are still packed to the gills with exciting discoveries which we’ll all be hearing more about as the months go by. Also, it gives it something to do now that the excitement is over.

One of the most exciting things I’ve seen lately is this huge juicy mosaic made by the LORRI instrument. It’s false colour to emphasise certain surface features and it’s just big enough to get slightly lost in. Emily Lakdawalla can tell you more details about it, but I just want to feast my eyes on how gorgeous this little world is…

False colour portrait

Pluto is watching you!

I sort of feel like Pluto might be a nice place to go hiking...

From the craters, the surface looks older here...

Marbled swirls on the shores of Pluto's heart...

It's not just me, right? It really does looks snowy, doesn't it...

Pluto has such odd landforms. Odd and really pretty!

Oh you beautiful little frostball. I can still barely believe we’ve finally visited you!

The original NASA release is here.

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