Posts Tagged‘sun’

Ancient Mars’ Earth-like Atmosphere Stripped by our Sun.

Mars is the most studied planet other than our own, currently playing host to no less than 7 different craft currently operating both in orbit and on its surface. It’s of interest to us due to its similarity to Earth, giving us an insight into how certain processes can affect planets differently. Mars is also the easiest of our sister planets to explore, being relatively close and having an atmosphere that won’t outright destroy craft that dare land on it. Still for all that research it still manages to surprise us, most recently by revealing the fact that liquid water still flows on it. We’re still far from done with it however and the MAVEN craft has just revealed some key insights into Mars’ atmosphere and the history behind its current state.


Mars’ atmosphere is extremely thin, over 100 times less dense than the atmosphere here on Earth. To put that in perspective that’s about the same density as the air here is on Earth at an altitude of about 30KM, or about 3 times as high as your typical jet airliner flies. It’s also almost all carbon dioxide with a small smattering of nitrogen and other trace elements. However it wasn’t always this way as numerous studies have revealed that it must have held a much thicker atmosphere in the past. What has remained something of a mystery is just how Mars came to lose its atmosphere and whether those same processes were in effect today. MAVEN, a craft specifically designed to figure this out, has made some key discoveries and it seems that the long held belief that the sun is to blame is true.

For a planet to lose its atmosphere there’s really only two places it can go. In some cases the planet itself can absorb the atmosphere, driving chemical reactions that pull all the gases down into more solid forms. This specific scenario was investigated on Mars however the lack of the kinds of minerals we’d expect to see, mostly carbonates given Mars’ mostly carbon dioxide atmosphere, means that this was unlikely to be the case. The second way is for it to lose the atmosphere to the vacuum of space which can happen in a number of ways, usually through the planet being unable to hold onto its atmosphere. This latter theory has proved to be correct although it’s far more interesting than Mars simply being too small.

In the past Mars would have looked a lot like Earth, a small blue marble wrapped in protective gases. Back then the core of Mars was still active, generating a magnetic field much like that on Earth. However, after a time, the core began to cool and the engine behind the giant magnetic field began to fade. As this field weakened the solar wind began to erode the atmosphere, slowly stripping it away. Today Mars’ magnetic field is around 40 times weaker than Earth’s, no where near enough to stop this process which is still continuing to this day. For Mars it seems that its diminutive core was what sealed its fate, unable to sustain its protective magnetic shield from the relentless torment of our sun.

Whilst this has been the prevailing theory for some time its good to get confirmation from hard data to support it. Our two closest solar relatives, Venus and Mars, provide insights into how planets can develop and what changes produce what outcomes. Knowing things like this helps us to understand our own Earth and what impacts our behaviour might have on it. Mars might not ever see its atmosphere again but at least we now know what it might have looked like once, and where it has gone.

The Sun’s Serenity.

Our sun is an incredibly violent thing, smashing atoms together at an incredible rate that results in the outpouring of vast torrents of energy into our solar system. Yet from certain perspectives it takes on a serene appearance, its surface ebbing and flowing as particles trace out some of its vast magnetic field. Indeed that’s exactly what the following video shows: a gorgeous composition of imagery taken from NASA’s Solar Dynamics Observatory. Whilst not all of us have the luxury of a 4K screen it’s still quite breathtaking to behold and definitely worth at least a few minutes of your time.

SDO has been in orbit for 5 years now keeping an almost unbroken eye on our parent star. Its primary mission is to better understand the relationship that our earth and the sun have, especially those which have a direct impact on daily life. To achieve this SDO is observing the sun in multiple wavelengths all at once (shown as different colours in this video) and on a much smaller timescale than previous craft have attempted. This has led to insights into how the sun generates its magnetic field, what it looks like and how the complex fusion processes influence the sun’s varying outputs like solar wind, energetic particles and variations in its solar output. Those images aren’t just rich with scientific data however as they showcase the sun’s incredible beauty.

So, how’s the serenity? 😉

Finally, Confirmation of How the Sun Works.

The sun is an amazing celestial object. Even though it looks about the same size as our moon when viewed from Earth’s surface it’s almost 400 times further away which should give you an idea of just how unfathomably large the sun is. It also heavily influences nearly every aspect of our Earth, providing nearly all of the energy that we, and all other lifeforms on this planet, consume on a daily basis. You’d be forgiven for thinking that we understood it completely however as whilst nearly anyone would be able to tell you that the sun is powered by fusion we, funnily enough, didn’t actually have proof of this.

That is, until now.

Giant_prominence_on_the_sun_eruptedIt sounds silly right? The theory of the sun being a giant ball of fusion has been around for 75 years and is pretty much established as a scientific fact. Indeed many of the observations that we’ve made of the sun support that theory and the small scale replicas we’ve made also seem to exhibit similar properties. However the surface of the sun, as we see it, doesn’t really tell us the whole story. Indeed the light emitted from the surface of the sun is hundreds of thousands of years old, spending most of its life worming its way out of the deeper layers of the sun. Should we want to verify that for sure we need to observe the products of fusion reactions happening now and, bar venturing into the sun itself, there’s only one way to do that: by observing one of our universe;’s most elusive particles, the neutrinos.

Specifically the neutrinos are called PP neutrinos, those which arise from the fusion of two protons to form helium. A fusion reactor on the scale of the sun generates countless numbers of these particles every second and, thanks to their near massless nature, they rush out unimpeded directly from the sun’s core. However the same properties which allow them to move at such great velocity away from the sun also prevents them being easily detected. Combine this with the fact that PP neutrinos carry less energy than regular neutrinos do you can see why definitive proof of fusion happening within the sun as eluded us for so long. Researchers in Italy though crafted an experiment to capture these ever elusive particles and their research has finally bore fruit.

The Borexino experiment uses a large device called a scintillator, essentially a large array of light detecting devices immersed in ultrapure water. It’s then buried deep underground (about 1.4KM) in order to shield it from cosmic rays and other stray radiation. This experiment was specifically designed to verify the solar output of neutrinos against the standard solar model in order to verify that fusion was indeed occurring within our sun. It began collecting data about 7 years ago and at the beginning of this year they had enough data to submit their final report. The results line up perfectly with what the standard solar model predicts which, for the first time, verifies that fusion is indeed occurring within our sun and has been for a very long time.

It may seem like a silly thing to do but verifying things like this is the key to ensuring that our understanding of the universe is in line with reality. We might have known that fusion was going on the sun for decades but without definitive proof we just had a good model that matched some of the observed behaviours. Now we know for sure and that means that our standard solar model is far more robust than it was previously. Thus, with this new information at hand, we can dive even deeper into the model, probing the various curiosities and figuring out just what makes our sun tick. We might not ever know everything about it but part of the fun of science is finding out what you don’t know and then trying to figure it out.


On The Importance of Sunscreen (Or What You Look Like in UV).

We Australians are leaders in many things we shouldn’t be, like our climbing obesity rates or per-capita carbon emissions. As it is with a lot of things like this the causes are readily preventable and it is up to us to take action in order to ensure that we lose our world leader status in these less-than-desirable categories. However there is one issue that, even despite years of campaigning and education programs, we Australians just never seem to get: we are the most likely people in the world to get skin cancer. This is an almost entirely preventable condition, one that requires almost no effort to ensure that you’re highly unlikely to suffer from it.

The video below shows just how effective sunscreen is at doing it’s cancer preventing job, blocking harmful UV rays:

Now the shocking discovery of UV freckles that many of the people in this video saw isn’t necessarily a bad thing (those are simply concentrated spots of melanin, your skin’s natural defence mechanism) however the application of sunscreen, as well as the glasses appearing to be opaque, should drive home the message that sunscreen does indeed work as advertised. UVA and UVB are both completely blocked by your regular over the counter sunscreens, providing full protection against the damaging rays of the sun. Sunglasses are also a vital if you’re spending a lot of time outdoors as continued exposure can lead to things like cataracts.

I know I’m probably preaching to the choir here but honestly when our incident rate of melanoma and other skin cancers is this high I feel it bears repeating. We’re a nation of people who love our beaches, sports and the outdoors and there’s really no reason that we should subject ourselves to unnecessary risks like this. Really taking 5 minutes to lather yourself up before hitting the beach isn’t a big ask and it could save you years of pain down the line.

You don’t have to end up as a statistic.

MESSENGER: Mercury’s First Artificial Satellite.

Mercury is a strange little beast of a planet. It’s the closest planet to our sun and manages to whip around it just under 88 days. Its “days” are 59 earth days long and whilst it’s not tidally locked to our parent star (like the moon is to us, always showing the same face to the earth) it is in a 3:2 spin-orbit resonance. This has led to some interesting phenomena when we’ve sent probes to image it as the only probe to ever visit it, Mariner 10, only managed to image 45% of the planet’s surface on it’s 2 encounter trip with the tortured little planet. That all changed a few years ago when MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) made its first approach to Mercury in January 2008 and sent back images of the as of yet unseen side of the planet. Ever since then MESSENGER has been on a long trajectory that will eventually bring it into orbit with Mercury and it will begin it’s year long mission of observations.

It just so happens that that day is today.

MESSENGER has been in space for an extremely long time, almost 7 years. You might be wondering why it has taken this craft so long to reach Mercury and the answer requires that you understand a little about orbital mechanics. You see as a heavenly body, in this case a satellite, moves closer to another body it will tend to speed up. This is known as the conservation of angular momentum and it’s the same principle that governs the increase in speed when you bring your arms in closer whilst you’re spinning. Thus for a satellite that’s launched from Earth to be able to orbit Mercury it has to shed all that extra speed so it can match up to it, otherwise it would just whiz right past it. Since doing this with a rocket is rather expensive (the fuel required would be phenomenal) NASA instead opts to shed velocity by a complicated set of maneuvers between planets, each of which removes a portion of the satellite’s velocity. This is cheap fuel wise but means the space craft will have to endure many years in space before it reaches its destination.

As I write this MESSENGER is making its final preparations to insert itself into an orbit around Mercury.  MESSENGER hopes to demystify the diminutive planet by providing hi-resolution imaging of the planet (there’s still 5% we haven’t seen yet), doing chemical analysis to determine the planet’s makeup and attempting to figure out why Mercury has a magnetic field. Probably the most interesting part of MESSENGER will be the last part as our current theories on planet formation point to Mercury being much like our moon with a solid core and no magnetic field to speak of. The presence of one there suggests that part of Mercury’s core is still molten and raises a number of questions over how planets and natural satellites like our moon form. It will also be the first ever artificial satellite of Mercury, something that still eludes many of the other planets in our solar system.

This is the kind of science that NASA really excels at, the stuff that just hasn’t been done before. It’s really amazing to see NASA flex their engineering muscle, designing systems that survive in the most unforgiving environment we know for decades and still function as expected. The next year will be filled with all kinds of awesome discoveries about our tortured little cousin Mercury and I for one can’t wait to see how the analysis of its magnetic field changes the way we model planet formations in the future.


Worlds Not of Our Own: The Hunt For Exoplanets.

Humanity, for the longest time, has been aware of planets outside the one that we reside on. Ask anyone today about the planets in our solar system and they’re sure to be able to name at least one other planet but ask them about any outside our solar system and you’re sure to draw a blank look. That’s not their fault however as the discovery of planets outside our solar system (which is by definition, not a planet but an exoplanet) is only recent, dating just over 20 years when the first was discovered in 1988. Since then we’ve discovered well over 500 more planets that exist outside our immediate vicinity and whilst their discovery is great none of them have yet been much like the one we currently call home.

In fact the vast majority of the exoplanets that have been discovered have been massive gas giants orbiting their parent stars at the same distance as Mercury orbits from our sun. This threw scientists initially as back then our current theories on solar system formation didn’t support the notion of large planets forming that close to their parent star. However as time we found more and more examples of such planets, these hot gas giants orbiting at velocities the likes we’d never seen before. The reason behind this is simple, the methods we use to find exoplanets are quite adept at finding these planets and not so much those which we’d consider potential homes.

The method by which the vast majority of exoplanets have been discovered is called the Radial Velocity method. As a planet orbits around its parent star the parent star also moves in tandem, tracing out an elliptical path that’s pinned around the common centre of mass between the two heavenly bodies. As the star does this we can observe changes in the star’s radial velocity, the speed at which the star is moving towards or away from this. Using this data we can then infer the minimum mass, distance and speed required to induce such changes in the planet’s radial velocity which will be the exoplanet itself. This method is prone to finding large planets orbiting close to their parent stars because they will cause larger perturbations in the star’s radial orbit more frequently, allowing us to detect them far more easily.

More recently one of the most productive methods of detecting an exoplanet is the Transit method. This method works by continuously measuring a star’s brightness over a long period of time. When an exoplanet crosses in front of its parent relative to us the star’s apparent brightness drops for the time it is in transit. This of course means that this method is limited to detecting planets and stars whose orbits line up in such a way to cause a transit like this. For earth like exoplanets there’s only a 0.47% chance that such planets will line up just right so we can observe them but thankfully this method can be done on tens of thousands of stars at once, ensuring that we discover at least a few in our search. Exoplanets discovered this way usually require verification by another method before they’re confirmed since there are many things that can cause a dip in a star’s apparent brightness.

There are of course numerous other methods to discover planets outside our solar system but for the most part the vast majority of them have been discovered by one of the two methods mentioned above. For both of them they are heavily skewed towards discovering big planets with short transit times as these produce the most observable effects on their parent stars. Still this does not preclude them from finding exoplanets like earth as shown with the recent discovery of Kepler10-b, a small rocky world in torturous conditions:

The planet, called Kepler-10b, is also the first rocky alien planet to be confirmed by NASA’s Kepler mission using data collected between May 2009 and early January 2010. But, while Kepler-10b is a rocky world, it is not located in the so-called habitable zone – a region in a planetary system where liquid water can potentially exist on the planet’s surface.

“Kepler-10b is the smallest exoplanet discovered to date, and the first unquestionably rocky planet orbiting a star outside our solar system,” said Natalie Batalha, Kepler’s deputy science team leader at NASA’s Ames Research Center in Moffett Field, Calif., at a press conference here at the 217th American Astronomy Society meeting.

Kepler-10b is the smallest transitioning planet to be confirmed to date and shows that it’s possible to discover worlds like our own using current technology. As time goes on and the amount of data increases I’m certain that we’ll eventually find more planets like these, hopefully a bit further out so they’ll be in the habitable zone. The Kepler mission is just a few months shy of its 2 year anniversary with at least another 1.5 years to go and if all goes well it should be returning swaths of data for us for the entire time to come.

I’m always fascinated by the latest discoveries in space even when they’re something like a molten mercury 564 light years away. Our technology is becoming more advanced with every passing day and I know that future missions will end up discovering millions of planets at a time with thousands of potentially life supporting worlds. It’s amazing to think that just 3 decades ago we couldn’t be sure that planets existed outside our solar system and today we know for sure there are more than 500 of them out there.

Ain’t science grand?

A Fortuitos Encounter.

I had struggled to get to sleep last night as my room was either blazingly hot or freezing cold thanks to the air conditioner that seems to operate on a whim all of its own. Still walking up this morning I didn’t feel too tired and went about looking for something to do. I had thought I would go to a beach since there were several within an hours drive from where I was, the question was which one of them to choose? I found a couple good sites on 5 of the local beaches and I eventually settled on Cocoa beach since it had a good amount of shops close by and seemed to be the biggest out of the lot.

Before I could leave though I had to attend to the matter of what to wear. Specifically the fact that I had worn pretty much everything I had brought over with me and they really needed a wash. Thankfully the hotel had a coin (well no cash value token) operated laundry on the second floor. I’d never used one of these before and it was novel, at least for the first 15 minutes until I realised my paranoid self couldn’t leave the clothes alone in case someone nabbed them. About an hour later I was out of there with half of my clothes clean and dry with the other being clean but still wet since they couldn’t be tumble dried. I strung them up in the laundry and then went about getting out of the hotel.

I hadn’t bothered doing my hair or anything since I knew I was going to ruin it not 30 minutes later when I arrived at the beach, so the first thing I did was take the top down on the Corvette. It was nice have the wind in my hair all the way down there although I quickly realised I had neither a beach towel nor any sunscreen to speak off. A quick detour into the local Walmart solved that problem and I continued on my way. No sooner had I got back onto the highway than did I see the sign for the next exit. It read “Kennedy Space Centre” and instantly my heart began to soar. I knew I was going to be going close to the KSC but I didn’t really know how close until I was crossing over the bridge. Just as I was getting over the apex I saw a structure I recognised, the Vehicle Assembly Building a giant hangar designed to house the shuttles while they’re being prepped for launch. I was like an excited kid, bobbing up and down in my seat at the mere site of it. I promised myself I wouldn’t go there until launch day, or failing that the last day before I left Florida.

With a giant grin on my face I continued on to Cocoa beach. It was getting on in the afternoon and I hadn’t had any lunch yet so I thought I’d get some food before heading down to the beach. No sooner had I pulled into a random car park to get my bearings than I heard the unmistakable sound of several large jet engines flying low overhead. Looking skyward I saw it was a Boeing C-17 being followed by two Blackhawk (I think, they didn’t look armed) helicopters, performing an in flight refuelling manoeuvre. A smile crept onto my face as I realised that I had lucked out and found the Cocoa Beach Airshow, the one I had been searching for but had be unable to find. What ensued was several hours of lying in the sun watching various aircraft perform all sorts of feats overhead. I even got to see the legendary Thunderbirds and their compliment of F-16s. Alas I had unknowingly left my camera back at the hotel, but I did grab a few iPhone pictures as momentos.

Once the show was over I went for a quick dip in the water. It was warm and inviting, the perfect way to finish off an afternoon of staring into the sky. After jumping out and towelling off a bit I realised there were no public change rooms in sight, nor any public showers. I made my way back to the car and then did the most awkward clothes change I’ve ever done, with half of myself sticking outside of the car and the other squished up against the centre console. I got there eventually however and was off on my way back home, content in the fact that I had lucked out considerably by choosing Cocoa Beach as my destination for that day.

There’s still been no word from my travel agent as to whether or not I can change the flights without incurring some kind of penalty. If I don’t have a response by tomorrow morning I’m going to take matters into my own hands and call the flight directly. I still haven’t found a hotel yet but I’m not terribly worried, we’re not in peak times over here yet and when I was staying at the airport I would bet on the fact that at least half of those rooms were empty. We’ll see though but if worst comes to worst I’ll just rent another car and sleep in that 😉

Hey, I might actually have a use for that stupid cellphone I bought. Awesome.

Piercing The Blazing Glare of Distant Suns.

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.