In the short time that I’ve been enamoured with all things space our understanding of the universe has changed significantly. Just a few years ago we had no idea how common multi-planet systems like our own were but today we know that a star is far more likely to have several planets than just a few. At the same time we’ve discovered so many more exoplanets that their discovery is now just routine and the count has tripled from the couple hundred to well over 600 confirmed discoveries (not including the multitude of current candidates). At the same time our understanding of how planets form has also been called into question and today brings news that may just turn our understanding on its head yet again.
Astronomers at the Kavli Institute for Particle Astrophysics and Cosmology released a paper back in February that detailed a very interesting idea. Using the observable effects of gravity in our galaxy combined with the observable mass (detected via microlensing events) they’ve deduced that there needs to be many more planets than what can be accounted for. What’s really curious about these planets is that they would have formed without a parent star:
But how can this be? Every star can’t have tens of thousands of planets ranging from Pluto-sized to Jupiter-sized. This planetary “excess” actually suggests the existence of planets that were born without a star – nomad planets. These planetary vagabonds somehow went through the planet-forming process in interstellar space, not in the dusty proto-planetary disk surrounding a young star.
This astonishing number was calculated by extrapolating a dozen “microlensing” events of nomad worlds passing in front of distant stars. When these nomad planets drifted in front of distant stars, they briefly focused the starlight with their gravity, causing the star to brighten. This brightening was captured by astronomers and the microlensing events could be analysed to reveal the characteristics of the nomad planets.
The idea of planets forming sans a parent star is an interesting one as it turns our current ideas of planet formation on their head. The generally accepted idea of planet formation is that a large accretion disk forms a star first, sweeping away a lot of matter away from it. After that the left over accretion belt begins coalescing into planets, asteroids and other heavenly bodies. Nomad planets then would have formed in smaller accretion disks without the required matter to form a star. If the paper is anything to go by this happens extremely often, to the tune of 100,000 times more often than there are stars in our galaxy.
Such planets are incredibly difficult to detect as we have no beacon to observe for wobbles (the radial velocity method). The only way we have to detect them currently is via microlensing and that means that the planet has to pass between us and another star for us to be able to see it. Even with so many planets and stars out there the chances of them all lining up are pretty slim which explains why we haven’t detected any to date. What we have found though are Brown Dwarfs and they’re quite interesting yet again.
Brown Dwarfs are what you’d call failed stars (or over-achieving planets, take your pick) as whilst they’re quite massive, on the order of 13 times the size of Jupiter at minimum, they still don’t have enough mass to ignite and become a fully fledged star. They do however generate quite a bit of heat which they give off as infra-red light. We can detect this quite readily and have identified many of them in the past. What’s intriguing though is that these Brown Dwarfs (or other nomad planets) could be used as stepping stones to the rest of the galaxy.
There’s a couple things that such planets could be used for. We already know that such planets could be used as a gravity slingshot to give current interstellar craft a speed boost en route to their destination. Another highly theoretical use would be to use these planets as refuelling stops if you were using some kind of hydrogen/helium powered craft. Such planets would also make excellent observation posts as they’d be far away from strong sources of light and radio waves, allowing them an extremely clear view of the universe. Indeed nomad planets could be quite the boon for an interstellar civilization, all we need is the technology to access them.
I’m very interested to see where this theory takes us and hopefully we’ll star seeing some nomad candidates popping up in the exoplanet catalogues in the next couple years. We might not yet be able to make use of them but their mere existence would tell us so much about the formation of heavenly bodies in our universe. At the same time it also raises a lot of questions that we haven’t considered before, but that’s the beauty of science.
About six months ago I wrote a post on the American Department of Defense’s new space craft the X-37B. At the time it was quite the curiosity with it being shrouded in secrecy as to its actual purpose but there was ample information about the craft itself floating around the internet. Since then though there really hadn’t been anything to write home about as the only information we could get about the craft was its orbit. Everything else remained classified.
It’s that one piece of information however that’s sent the satellite watchers into a flurry. The X-37B’s orbit has been well known for quite some time and many amateur astronomers have been tracking its position since launch. 2 months ago however the diminutive cousin of the shuttle changed its orbit significantly, boosting itself a good 29KM higher above the earth’s surface. Amateur astronomers trying to catch a glimpse of the craft soon after the manoeuvres couldn’t find the craft and the hunt was on to find where it had gotten itself off to. It wasn’t too long before they found it however and the reclusive craft disappeared back into seclusion.
Then just a couple weeks ago they lost track of the craft yet again, signalling that it had made yet another in orbit adjustment. Two weeks of searching later and the craft was then spotted again around 54KM lower than it was previously. With the mission time over 180 days at this point the craft, according to specifications provided by the military, still has a good 90 days of in orbit time before it needs to return to the surface. Thus whilst the true nature of this change is not known you can probably bet that it’s not going to be coming home soon, and that brings up the possibility that the last few changes had another purpose in mind.
Whilst it was probably nothing more than just testing their orbit changing capabilities the conspiracy nut in me won’t be satisfied until I dig a little deeper into what they might be doing. We know that the X-37B has a decent payload bay on it but we have no idea whether it was loaded up or not. If it wasn’t that opens up the possibility of the DoD doing some in orbit satellite capture for reconnaissance or possibly bringing down to earth. The orbit of the X-37B is a strange one though with its inclination being 40 degrees, an orbit not shared by a lot of other craft. However there are a few as this site shows but unfortunately for my caged conspiracy nut they’re all at higher orbits and there’s nothing particularly interesting about any of them.
So much for that then.
In all seriousness the mission is more than likely all about testing the longevity of the components that have gone into making the X-37B and little else. The on orbit dancing this craft has been doing verifies that it’s capable of shifting itself around significantly and that the control systems of the craft are still functional after 6 months in high orbit. Had this been launched into a more populated area of space then I might contend that they were testing its ability to intercept other craft but right now it appears that the USA is just making sure their new toy works as it was designed to.
Future missions might be more exciting, however.
Staring up at the night sky is one of the most humbling experiences I’ve ever felt. Each of those tiny points of light is a sun burning furiously in a runaway fusion reaction. By comparison I, a mere human, am no more than a tiny fleck in comparison to one of those stars and barely even an atom when compared to the teaming masses of stars that make up that beautiful nightscape. Even more daunting then is the possibility that each of those twinkling stars plays host to a solar system like our own with dozens of planets just waiting for discovery. Our hunt for these planets has brought us hundreds of large gas giants who by the nature have been very easy to detect. Direct imaging of these planets has been nigh on impossible with the precious few we’ve managed to glimpse being extraordinary examples, rather than the rule. That is set to change, however.
Light, you see, is a funny thing. For centuries scientists pondered over the modelling of it, with the two dominant theories describing it as either as a particle or a wave phenomena. Problem is that light didn’t fit neatly into either of the models, requiring complex modelling in order to fit its behaviour into either the particle or wave category. Today many of the properties of light are now explained thanks to Einstein’s theory of wave-particle duality but for a long time one of the most confounding properties of light was that light can interfere with itself. You’ve probably seen this demonstrated to you back in college via the double slit experiment where you get a pattern of light and dark from a single source of light. At the time I didn’t think much of it past the initial intrigue but my discovery of my passion for space many years later had me thinking about how this might be used.
I had been reading about the hundreds of exoplanet discoveries for a while when I heard of 2M1207b which is thought to be the first directly imaged planet outside our solar system. It’s an exceptional planet being an extremely hot gas giant orbiting a very dim companion star. For systems like our own there would be no chance of seeing any planets from the outside thanks to our extremely bright sun and our relative proximity to it. Still knowing that light had the novel ability to cancel itself out I had wondered if we could say build an apparatus that forced light from a parent star to cancel itself out, letting us peer behind the blazing might to see what lie beneath.
It wasn’t until a few years later when I stumbled across the idea of a StarShade which had been proposed many years previously. In essence it would function as an augmentation to any space based telescope positioning itself perfectly in front of the parent star and reducing its brightness by a whopping 10 billion times. In comparison then the tiny planets which were once outshone would glow bright enough for the telescopes to be able to see them directly, hopefully leading to direct detection of many planets orbiting the star. Unfortunately it appears that this project is now defunct but that doesn’t mean the idea doesn’t live on in other forms.
Most recently an international collaboration of scientists developed a Apodizing Phase Plate coronagraph which is in essence a scaled down version of a starshade that can be installed in current telescopes:
Installed on the European Southern Observatory’s Very Large Telescope, or VLT, atop Paranal Mountain in Chile, the new technology enabled an international team of astronomers to confirm the existence and orbital movement of Beta Pictoris b, a planet about seven to 10 times the mass of Jupiter, around its parent star, Beta Pictoris, 63 light years away.
At the core of the system is a small piece of glass with a highly complex pattern inscribed into its surface. Called an Apodizing Phase Plate, or APP, the device blocks out the starlight in a very defined way, allowing planets to show up in the image whose signals were previously drowned out by the star’s glare.
It’s not just planets that this device helps discover either, it can also help detect distant objects that are hidden behind brighter ones. This enables telescopes to become even more powerful than they once were with minimal modifications. Probably the best part about this is that they’re already using them on the Very Large Telescope in Chile, proving that technology is much more than just a theory.
There’s so much to discover in our universe and it always gets me excited to see these pieces of technology that allow us to pull back the veil and peer ever further into the deepest parts of space. It’s so humbling to know that you’re just a tiny piece of a seemingly infinite universe yet it’s so enthralling that I lose myself for hours just staring up at the night sky. I feel so privileged to be living in a time were our knowledge of this universe is increasing at an ever accelerating rate yet we’re still left wondering at the awesome beauty that’s put before us.
This year is the Internation Year of Astronomy to celebrate 400 years of astromincal observation and study. This is a great oppotunity for anyone who has even a mild interest in the stars and our place in the universe to get involved in some astronomy. I know that I will be spending the better part of this year staring up at the sky and hopefully, sharing it with everyone who is willing 🙂
I think what puts most people off astronomy is the idea that you have to get up at 1am and drive out to remote locations to get a good view of the stars. Whilst that’s true if you want the best view it doesn’t mean you can’t do some pretty good observing from the comfort of your backyard. In fact there are some great things to see and you don’t even need a telescope, although I’d reccomend picking up a pair of binoculars if you’d like to get a better look at some things.
So, what are some interesting sights to see? Personally I’d reccomend starting off with the Moon, since it’s big, bright and with a pair of binoculars you can seem some incredible detail. The other favourites are Mars, Jupiter and Venus, since they’re all fairly bright and can be seen with the naked eye.
One of my all time favourites will be the International Space Station, which you can plot sighting times using NASA’s Skywatch program. Just select your city and it will give you times that you can view the station.
If you’re hungry for more, the best website I’ve found for sightings of many different astronomical objects is Heaven’s Above. They’ve even got a great guide for deciphering all the terms that use so even if you’ve never done this kind of thing before, you’ll be able to find what you want in the sky.
I spent a weekend down at the coast when the moon was full just a couple weeks ago. I got some fantastic pictures whilst I was lazing on the beach long into the night. I’ll be sure to share them all with you here.