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Voyager 1 Has Left the Solar System
Voyager 1 has officially left the building! Image Credit: NASA/JPL-Caltech
A new space milestone has just occurred, or occurred around August 2012. The Voyager 1 space probe that was launched on September 5, 1977 has finally left the solar system. Thirty five years after its launch the audacious probe enters a new stage in its mission, exploring the region of space outside of the Sun’s influence.
The Sun’s influence in space extends way beyond the orbit of Neptune. We know that beyond the inner planets lies the Kuiper Belt which is home to Pluto and many, many other dwarf planets. Finally at about 18 billion kilometers from the Sun and four times the distance between the Sun and Neptune, is a region known as the heliopause. The heliopause is the region where the solar wind from the Sun collides with the interstellar medium, a collection of particles which is the collection of gas, dust, and cosmic rays. The solar particles are so dilute once it reaches the interstellar medium that the heliopause is considered the end of the Sun’s influence (although its gravity extends well beyond the heliopause to the Oort Cloud).
A new paper that has been published confirms the conclusions that were drawn about the solar wind particles back in December. Data from the probe showed that the number of subatomic particles coming from the Sun dropped dramatically sometime around August 2012 while the number of cosmic rays from the interstellar medium spiked. While it’s not exactly new news, it still is exciting to think about. There is now a man-made object outside of the solar system and is still able to communicate with us 18 billion kilometers away.
Eventually the plutonium inside of Voyager will stop producing electricity and communications will cease. At that point, the probe will continue to sail in the direction of the galactic center. There is an estimated 10-15 years of power left on the probe so we need to enjoy it while it lasts. It will be a long time before human travelers can journey this far from our home, but we’ll do it one day.
Comets: Why the Solar System Rocks!
When we look back, 2013 may be remembered as the Year of the Comets. As I’m sure you may have heard already we have two potentially immensely wonderful comets heading our direction this year; the first of which will be its closest to the Sun on March 10th. The more you learn about comets the more you appreciate how amazing the solar system is! When you consider what comets are, how they get here, and what on Earth makes them shine so beautifully then fade into oblivion for thousands of years you are left with a sense of awe because the answer to all of these questions is…the Sun.
Thanks to Nicolas Copernicus we know that the Sun is the center of our solar system and that everything in the solar system orbits the Sun on regular and predictable paths. You have the 8 major planets, the asteroids in the asteroid belt, the minor, or dwarf, planets of a region called the Kuiper belt, of which Pluto is a member, then far, far away from the Sun at a distance of almost one light year you is the region known as the Oort Cloud. The Oort cloud is a massive region of space mostly by tiny chunks of ice and rock left over from the formation of the solar system. These chunks of ice and rock are so far away from the Sun that they are approximately one-quarter the distance to the nearest star, Proxima Centauri. The Sun is barely more than a pin point of light out here and its gravity is just strong enough to keep these tiny chunks of ice loosely in orbit. However, the gravity is so weak that objects in the Oort Cloud are influenced by passing stars and the Milky Way itself. All it takes is the slightest gravitational nudge from another star to dislodge an ice chunk from its happy orbit and send it drifting slowly towards the inner solar system.
Cutaway drawing of Oort Cloud Image credit: NASA/JPL
This is how we believe most long period comets are born. Long period comets are comets with highly eccentric (or lopsided) orbits that span between 200 and thousands, or even millions of years. Comet McNaught that passed through the solar system back in 2007 is a long period comet with an orbit of about 92,600 years. It’s safe to say that we won’t see that bad boy again in our lifetimes!
Once the ice chunk is dislodged from its orbit in the Oort Cloud it begins its long, slow journey towards the Sun. The Sun’s gravity begins to pull it in towards itself on an epic tour of the solar system that spans almost an entire light year (one light year is 6 trillion miles). Comets are typically no bigger than a hundred or so meters across but the Sun causes something to happen on their surface that makes them spectacular sights in the night sky. Out in the Oort Cloud it is mind-bogglingly cold. Before they turn into comets the chunks rocks and dust mixed with chunks of frozen water, ammonia, carbon dioxide or methane that are so cold they’re as hard as steel. But once they get close enough to the Sun they begin to heat up.
Once the comet arrives in the inner solar system the Sun’s heat begins to melt the ice and it begins to evaporate and glow brightly which is caused by solar ionization. The glowing cloud of evaporating gas is called the coma. Once the coma is formed the tell-tale…well, tail of the comet begins to form as the solar wind from the Sun blows against the comet. The comet, tail, and coma steadily brighten as the comet gets closer and closer to the Sun. They also begin to pick up more speed the closer they get. By the time a comet is visible on Earth it already has a dazzling coma and tail that can be as bright as the stars and perhaps even the planets!
It is once the comet is within the orbit of Mercury that the fate of the comet is determined. Most comets slingshot around the Sun at a safe distance that they make it around without a problem and begin their lonely journey back out of the solar system into oblivion. Other comets called sun grazers get so close to the Sun that they actually pass through the Sun’s upper atmosphere, the photosphere, or even the solar corona where the temperature is millions of degrees Fahrenheit. Some sun grazers make it out intact while others break apart and disintegrate, much like a frozen coffee mug when boiling water is poured in it. Others still are known as sun divers which literally plunge right into the Sun and are never heard from again.
Comet Hale Bopp in 1997
Once the point of perihelion, or the comets closest approach to the Sun is reached the comet begins it’s journey back to where it came from. Depending upon the positioning of the planets on its return journey, some comets stay in orbit around the Sun and will eventually return. If a planet’s gravity nudges the comet on the way out it could end up being ejected from the solar system entirely and be doomed to roam the void of interstellar space forever. Whatever the fate of the comet we get to observe the magnificent effects of the Sun on them from the Earth, both visually and scientifically.
This year we have two potentially dazzling and memorable comets heading our way! The first of which is named comet C/2011 L4 PANSTARRS, or PANSTARRS for short. With a perihelion of March 10, 2013 it promises to put on a nice show throughout the months of March and April. Observers in the northern hemisphere won’t be able to see the comet until after its perihelion though. So be sure to get outside during clear nights in March and April to see this orbiting rocky ice clump. Currently, PANSTARRS is projected to get as bright as the planet Venus if everything goes according to plan with its passage around the Sun. PANSTARRS will be bright and low in the sky about 30 minutes after sunset in mid-March.
If you miss PANSTARRS or couldn’t get enough comet viewing action for one year you’re in luck! Even brighter and more spectacular than PANSTARRS will be comet ISON in the fall months. ISON is currently close to Jupiter on its voyage towards the Sun but will begin to be visible in binoculars in the beginning of October. By November 1st ISON will be within the orbit of Earth and should be a spectacular -6 magnitude! Astronomers measure brightness by magnitude with the lower the number being a brighter object. The planet Saturn is +1 magnitude and the brightest star in the sky, Sirius, is -1.46. By the time it reaches its perihelion on November 28th it is expected to reach a -12.6 magnitude which is as bright as the full moon! That means that as it passes next to the Sun it will be visible during the daytime if you use your hand to cover the Sun! ISON should put on a show of a lifetime during November and December and will truly be something to tell your kids and grandchildren about because ISON will likely never return. If you own a telescope or a pair of binoculars make time to get out with your friends and observe this marvelous comet. This one has the potential to be the brightest comet in recent history, brighter even than the famous Halley’s comet.
Comet McNaught from 2007
It never ceases to amaze me that all the wonderful things we love about comets, their beautiful tails and diamond-like sparkle is all due to the power of the Sun. We live in an active solar system that is constantly moving and it is all thanks to the Sun’s influence.
Brace Yourself, The Venus Transit is Coming!
Yes that’s right! A little over 24 hours remain until the most spectacular astronomical event of the year! However, make sure you check the weather forecast for your area before venturing out to watch the transit. The entire east coast and much of the southeast of the USA could be blanketed by showers and overcast skies most of the day tomorrow. If you’ve been building up your excitement for the past several months like I have, start to release that excitement because there is a strong possibility that as much as 75 percent of the country won’t be able to see the transit due to bad weather. Even though the transit is over 24 hours away, as I watch the grey clouds roll in I’m beginning to get that deflating feeling like I had a Venus-sized balloon of excitement for the transit and now someone is rapidly letting all the air out of that balloon.
Rain or shine I’m going to be watching the weather minute by minute to find out what’s going on. Don’t abandon your plans quite yet. You really never know with the weather. There may be a break in the clouds long enough to watch the ingress of the planet. Regardless, I tested my homemade solar filter yesterday morning and I must say that it works to perfection! I opted to make one myself instead of buying an expensive one from a vendor. I used the visual density Baader Solar film from Astro-Physics and constructed a housing for it.
DIY solar filter success
The resulting image was spectacular! Even though it was hard to get a full image of the sun on my phone’s camera I could still see it perfectly through the 25mm eyepiece. I suspect it has something to do with the fact that the aperture is now offset and a lot smaller than the normal aperture. A great deal of detail could be seen on the sun such as sunspots 1497, 1496, 1493, and 1494, as well as a strange black smudge near the center of the disk which I’m not sure about. The resulting image is much dimmer than the sun funnel technique and I think provides much better contrast on the surface for defining sunspots. Regardless of whether I can view the transit, I’m very pleased with my filter and hope to get lots of use out of it. Heck, I only used a small bit of the Baader film so I can make more if I want!
Partial image of the sun’s disk
My fingers are crossed for good weather and if you’re planning on viewing the transit best of luck to you as well! Clear skies!
The Sun Funnel
In preparation for the upcoming Venus transit on June 5th I was looking at cheap, but effective ways to view the sun with my telescope. I wasn’t very interested in buying a full aperture solar filter for my 10″ scope so I was thrilled when I found www.transitofvenus.nl. The accessory proposed on this site is the sun funnel, a rear projection, group viewing tool for the viewing the sun. The sun funnel is very easy to make and costs just about $20 to make.
The funnel consists of a large fuel funnel, rear projection screen, two hose clamps, and an eyepiece. I say it costs about $20 assuming that you own a telescope eyepiece already, if not you’ll have to pay a bit more. You don’t need an expensive eyepiece, just one that fits the focal length of the telescope and the length of the funnel to give you an optimal image size. More info on the eyepiece can be found on the website. The rear projection screen can easily be ordered online and costs about $17 for one square foot.
I put my sun funnel together this past Monday and attached it to my scope but alas, the sun had almost set and was behind the trees in my backyard. I had to wait until Friday evening after work to get another good viewing chance, but I was not disappointed! Once the image is focused correctly my 25mm eyepiece projected an image about 75% of the funnel’s diameter! The image is still rather bright, but is by all means safe to look at with the naked eye (although sunglasses might make it more comfortable).
EDIT: I would also highly recommend building an aperture stop of some sort to reduce the amount of light gathered by the scope. You can use any kind of material really, but all you do is cut out a circle about 2″ in diameter in whatever material you’re using (a cardboard box works well) offset from the center so that you don’t cover up the secondary mirror (for reflectors). This reduces the aperture of your scope from say 10″ to 2″ which is perfectly fine for viewing an object as bright as the sun.
Once set up the image of the projected sun is razor sharp! As the picture below shows, once the image is focused on my phone the detail on the disk is stunning! Several sunspots are visible dotting the fiery surface of the star. In the center left and clearly visible is the large sunspot 1459. Three other pairs of sunspots form an isosceles triangle around 1459 in the center. Not bad for my first attempt at viewing the sun. I’m really looking forward to viewing the transit through the sun funnel in less than two months!
Focused image with sunspots visible
Northern Lights in Your Neighborhood?
Tonight, January 24th could potentially stage a quite rare celestial show for the United States. The solar storm and resulting coronal mass ejection (CME) on the sun is hurtling hundreds of millions of subatomic particles towards the Earth at breakneck speed. But fear not! The Earth is well suited to deal with radiation blasts such as these thanks to our spinning molten iron core which generates a magnetic field around the planet. The particles from the sun “excite” the magnetic field and glow causing the awe-inspiring show we call the Aurora Borealis, or northern lights. This is a particularly strong CME, the strongest one since 2005 to be exact, on a scale of 1-10, this one’s a 9. The sun’s electromagnetic storms rage in approximately 11 year cycles and the current cycle is due to peak over the next 12-18 months. So this kind of activity will increase in frequency (but only a little in intensity). The magnitude of this storm will produce very favorable viewing conditions for those living in the northern hemisphere, particularly those in Canada, northern Europe, the UK, and the northern half of the U.S. potentially as far south as the Carolinas!
If you’re curious about whether or not you can expect to see some aurora action there is a helpful map from the NOAA (National Oceanic and Atmospheric Administration) that shows the predictable range of the auroras. But don’t get all down on life if you live south of the line, mother nature can misbehave and do things even the best scientists can’t predict so take heart! If it’s a clear night just head outside and take a look for maybe an hour or so and if there’s no aurora, you’ll still get some great views of Jupiter, Mars, and Venus! If you live on the east coast the moon is traversing the sky with the sun today so it will be nice and dark without the moon so all signs are pointing to a great viewing night! Best of luck to everyone!
Thanks to Bad Astronomy for providing the link to the NOAA page!
