Posted on by David Dickinson

An Incredible Time-lapse of Venus Passing Through Inferior Conjunction

Image credit: Shahrin

Some of the most amazing celestial sights are hidden from our view in the daytime sky. Or are they? We recently challenged readers to try and follow the planet Venus through inferior conjunction as it passed between the Earth and the Sun on January 11th. Unlike the previous pass on June 6th, 2012 when Venus made its last transit of the Sun for the 21st century, the 2014 solar conjunction offered an outstanding chance to trace Venus’s path just five degrees from the Sun from the dusk and into the dawn sky.

Expert astrophotographers Shahrin Ahmad based in Sri Damansara, Malaysia and Paul Stewart observing from New Zealand took up that daily challenge as Venus neared the limb of the Sun, with amazing results. Now, Shahrin has also produced an amazing time-lapse sequence of Venus passing through inferior conjunction.

You can actually see the illuminated “horns” of Venus as they thin, extend, and rotate around the limb as the planet passes the Sun.

And it’s what’s more incredible is that the capture was completed in the daytime. But such a feat isn’t for the unskilled. Shahrin told Universe Today of the special safety precautions he had to take to acquire Venus so close to the Sun:

“Since Venus was getting closer each day towards conjunction, I found it far too dangerous to find visually, either using the main telescope or the finderscope.”

Instead, Shahrin relies on computerized software named Cartes du Ciel to drive his Skywatcher EQ6 mount and pinpoint Venus in the daytime sky.

“The sky in Kuala Lumpur is never clear from here, thus it rarely appears dark blue, making it almost impossible to spot Venus visually, especially when it is less than 10 degrees from the Sun.”

Shahrin elaborated further on his special solar safety precautions:

“I always start with all covers in place and the solar filter on the main telescope. I will slew the telescope to the Sun, make some slight repositioning adjustments, and then synchronize the telescope to the new position. After ensuring the Sun is visible and centered on the computer screen, I slew to Venus. Once the mount has stopped in position, I remove the solar filter and replace it with a makeshift cardboard extender mounted on the existing dew-shield. This ensures that any direct sunlight is totally blocked from entering the optics.”

Shahrin notes that 90% of the time, Venus with appear on the computer screen after aligning. Otherwise, a brief spiral search of the field will slide it into view.

Shahrin observes from his ShahGazer Observatory, a roll-off-roof observatory just outside of Kuala Lumpur. He used the Skywatcher 120ED refractor pictured for the captures, with a 2x Barlow lens to achieve a focal length of 1800mm. Shahrin’s main camera is a QHY CCD IMG132e, and the rig is mounted on a Skywatcher EQ6.

Credit: Shahrin Ahmad.
A closeup of Sharin’s barlow and camera rig. Credit: Shahrin Ahmad.

“The experience of being able to track Venus approaching inferior conjunction over the Sun afterwards is exhilarating,” Shahrin told Universe Today. “It felt like watching and waiting for a total eclipse of the Sun, but in slow motion!”

Shahrin also counts himself lucky to have had a string of clear days leading up to and after inferior conjunction.

Shahrin’s capture of Venus 5 degrees from the Sun just 8 hours before inferior conjunction may also be a record. That’s a closer apparent separation than our visual sighting of Venus 7 hours and 45 minutes after inferior conjunction on January 16th 1998 as seen from North Pole Alaska, when the planet passed 5.5 degrees from the limb of the Sun.

“I’ve also noticed that in some of the photos, we can see a slight ‘glint’ of sunshine on part of Venus’ atmosphere,” Shahrin noted to Universe Today. “(This sighting) was actually confirmed by the RASC Edmonton Centre in Canada via their Twitter feed.”

An amazing capture, indeed. Venus is now back in the realm of visibility for us mere mortal backyard observers low in the dawn sky, shining at a brilliant magnitude -4.3. Expect it to vault up in a hurry for northern hemisphere observers as the favorable angle of the ecliptic will give it a boost in the dawn. Venus is also headed towards a spectacular 0.2 degree conjunction with Jupiter this summer on August 18th: expect UFO sightings to rise correspondingly.  The Indian Army even briefly mistook the pair for Chinese spy drones early last year.

The waning crescent Moon approaches Venus on the morning of January 28th, 2014. Created using Stellarium.
The waning crescent Moon approaches Venus on the morning of January 28th, 2014. Created using Stellarium.

Venus will spend most of 2014 in the dawn sky and is headed for superior conjunction on October 25th, 2014. Venus spent a similar span in the dawn for the majority 2006, and will do so again in 2022. It’s all part of the 8-year cycle of Venus, a span over which apparitions of the planet roughly repeat. And the next shot we’ll have at inferior conjunction?  That’ll be on August 15th, 2015 for favoring the southern hemisphere and March 25th, 2017 once again favoring the northern, when the planet very nearly passes as far from the Sun as it can appear at inferior conjunction at 8 degrees.

Congrats to Shahrin on his amazing capture!

-Follow the stargazing adventures of Sharin Ahmad on Google+ and as @shahgazer on Twitter

-Got pictures of Venus? Send ‘em in to Universe Today.

 

Posted on by Jason Major

Why Is the Solar System Flat?

It’s no mystery that the planets, moons, asteroids, etc. in the Solar System are arranged in a more-or-less flat, plate-like alignment in their orbits around the Sun.* But why is that? In a three-dimensional Universe, why should anything have a particular alignment at all? In yet another entertaining video from the folks at MinutePhysics, we see the reason behind this seemingly coincidental feature of our Solar System — and, for that matter, pretty much all planetary systems that have so far been discovered (not to mention planetary ring systems, accretion disks, many galaxies… well, you get the idea.) Check it out above.

Video by MinutePhysics. Created by Henry Reich
Continue reading “Why Is the Solar System Flat?”

Posted on by Shannon Hall

Surprise! Fomalhaut’s Kid Sister Has a Debris Disk Too

Image Credit: Amanda Smith

The bright star Fomalhaut hosts a spectacular debris disk: a dusty circling plane of small objects where planets form. At a mere 25 light-years away, we’ve been able to pinpoint detailed features: from the warm disk close by to the further disk that is comparable to the Solar System’s Kuiper belt.

But Fomalhaut never ceases to surprise us. At first we discovered a planet, Fomalhaut b, which orbits in the clearing between the two disks. Then we discovered that Fomalhaut was not a single star or a double star, but a triplet.  The breaking news today, however, is that we have discovered a mini debris disk around the third star.

Fomalhaut is massive, weighing in at 1.9 times the mass of the Sun. And at such a close distance it’s one of the brightest stars in the southern sky. But its two companions are much smaller. The second star, Fomalhaut B, is 0.7 times the mass of the Sun and the third star, Fomalhaut C, a small red dwarf, is 0.2 times the mass of the Sun.

Fomalhaut C orbits Fomalhaut A at a distance of 2.5 light-years, or roughly half the distance from the Sun to the closest neighboring star.  It was only confirmed to be gravitationally bound to Fomalhaut A and Fomalhaut B in October of last year.

“The disk around Fomalhaut C was a complete surprise,” lead researcher Grant Kennedy of the University of Cambridge told Universe Today. “This is only the second system in which disks around two separate stars have been discovered.”

Relatively cool dust and ice particles are much brighter at long wavelengths, allowing telescopes like the Herschel Space Telescope, to pick up the excess infrared light. However, Herschel has a much poorer resolution than an optical telescope so the image of Fomalhaut C’s disk is not spatially resolved — meaning the brightness of the disk could be measured but not its structure.

Kennedy’s team’s best guess is that the disk is quite cold, around 24 degrees Kelvin and pretty small, orbiting to and extent of 10 times the distance from the Earth to the Sun. But it’s likely that it’s similar to Fomalhaut A’s disk in that it’s bright, elliptical, and slightly offset from its host star. All three characteristics suggest that gravitational perturbations may be destabilizing the cometary orbits within the disks.

“As a stellar system Fomalhaut’s gotten very interesting in the last year,” Kennedy said. With two wide companions “it’s not obvious how the configuration came about. Forming one wide companion is not so hard, but getting a second is very unlikely. So we need to come up with a new mechanism.”

Kennedy is currently working on figuring out what exactly this “new mechanism” is and he thinks the debris disk around Fomalhaut C will provide a few helpful hints. His best guess is still under construction but it’s likely that a small star is disturbing the system.

The next step will be to watch the stellar system over the next few years in order to measure their orbits exactly. With precise motions we just might be able to see what is interrupting the system.

“We think these observations will provide a good test of the theory,” Kennedy told Universe Today. They just might “solve the mystery of why the Fomalhaut system looks like it does.”

The paper has been published in the Monthly Notices of the Royal Astronomical Society and is available for download here.

Posted on by Tammy Plotner

Milky Way Shakes, Rattles and Rolls…

Three stages of the evolution of the galaxy simulation used to model the Milky Way. (Credit: AIP)

For decades astronomers have puzzled over the many details concerning the formation of the Milky Way Galaxy. Now a group of scientists headed by Ivan Minchev from the Leibniz Institute for Astrophysics Potsdam (AIP) have managed to retrace our galaxy’s formative periods with more detail than ever before. This newly published information has been gathered through careful observation of stars located near the Sun and points to a rather “moving” history.

To achieve these latest results, astronomers observed stars perpendicular to the galactic disc and their vertical motion. Just to shake things up, these stars also had their ages considered. Because it is nearly impossible to directly determine a star’s true age, they rattled the cage of chemical composition. Stars which show an increase in the ratio of magnesium to iron ([Mg/Fe]) appear to have a greater age. These determinations of stars close to the Sun were made with highly accurate information gathered by the RAdial Velocity Experiment (RAVE). According to previous findings, “the older a star is, the faster it moves up and down through the disc”. This no longer seemed to be true. Apparently the rules were broken by stars with the highest magnesium-to-iron ratios. Despite what astronomers thought would happen, they observed these particular stars slowing their roll… their vertical speed decreasing dramatically.

So what’s going on here? To help figure out these curious findings, the researchers turned to computer modeling. By running a simulation of the Milky Way’s evolutionary patterns, they were able to discern the origin of these older, slower stars. According to the simulation, they came to the conclusion that small galactic collisions might be responsible for the results they had directly observed.

Smashing into, or combining with, a smaller galaxy isn’t new to the Milky Way. It is widely accepted that our galaxy has been the receptor of galactic collisions many times during its course of history. Despite what might appear to be a very violent event, these incidents aren’t very good at shaking up the massive regions near the galactic center. However, they stir things up in the spiral arms! Here star formation is triggered and these stars move away from the core towards our galaxy’s outer edge – and near our Sun.

In a process known as “radial migration”, older stars, ones with high values of magnesium-to-iron ratio, are pushed outward and display low up-and-down velocities. Is this why the elderly, near-by stars have diminished vertical velocities? Were they forced from the galactic center by virtue of a collision event? Astronomers speculate this to be the best answer. By comparison, the differences in speed between stars born near the Sun and those forced away shows just how massive and how many merging galaxies once shook up the Milky Way.

Says AIP scientist Ivan Minchev: “Our results will enable us to trace the history of our home galaxy more accurately than ever before. By looking at the chemical composition of stars around us, and how fast they move, we can deduce the properties of satellite galaxies interacting with the Milky Way throughout its lifetime. This can lead to an improved understanding of how the Milky Way may have evolved into the galaxy we see today.”

Original Story Source: Leibniz Institute for Astrophysics Potsdam News Release. For further reading: A new stellar chemo-kinematic relation reveals the merger history of the Milky Way.

Posted on by Susie Murph

Carnival of Space #337

Carnival of Space. Image by Jason Major.
Carnival of Space. Image by Jason Major.

The tent is up! This week’s Carnival of Space is hosted by Pamela Hoffman at the Everyday Spacer blog.

Click here to read Carnival of Space #337.

And if you’re interested in looking back, here’s an archive to all the past Carnivals of Space. If you’ve got a space-related blog, you should really join the carnival. Just email an entry to [email protected], and the next host will link to it. It will help get awareness out there about your writing, help you meet others in the space community – and community is what blogging is all about. And if you really want to help out, sign up to be a host. Send an email to the above address.

Posted on by Nancy Atkinson

Rosetta Wakes Up, Phones Home, Starts Tweeting

The Rosetta team at ESA’s space operations center in Darmstadt reacts after receiving a signal from the spacecraft. Credit: ESA.

The silence from the live video feed from the ESA’s space operations center in Darmstadt, Germany was almost deafening. Scientists and engineers were waiting to receive a signal from the Rosetta spacecraft, which was supposed to come out of hibernation today to begin its mission to Comet 67P/Churyumov-Gerasimenko in earnest. Finally, after waiting nearly 45 minutes into the window of time when the spacecraft was supposed to send a signal, a little blip appeared on the screens of the spectrum analyzers and the room erupted in cheers.

Data monitors from Rosetta showing the signal received back on Earth from the spacecraft. Credit: ESA.
Data monitors from Rosetta showing the signal received back on Earth from the spacecraft. Credit: ESA.

“After waiting over two and a half years, what is three-quarters of an hour!” said Fred Jansen, ESA’s Rosetta mission manager. “The spacecraft is there, it’s awake and the science team knows there are two busy years ahead of them. Now we have to work hard. Thanks to the team that achieved this.”

“I think I can speak on behalf of everyone here and everyone on Twitter: that was rather stressful!” said Matt Taylor, Rosetta project scientist. “The work begins now and I think we’ll have a fun-filled two years ahead, so let’s get on it!”

Soon after the signal arrived, the mission Twitter feed came alive, Tweeting “Hello World” in multiple languages.

Later in the day, as the team checked out the spacecraft, everything appeared in order and working well as systems began to start operating:

Rosetta was placed into hibernation in June 2011, with only the computer and several heaters remaining active as the spacecraft cruised out to nearly 800 million km from the warmth of the Sun, beyond the orbit of Jupiter.

Today, as Rosetta’s orbit came back to within 673 million km from the Sun, there was enough solar energy to power the spacecraft fully again and Rosetta’s pre-programmed internal ‘alarm clock’ woke up the spacecraft after a record 957 days of hibernation. After warming up its key navigation instruments, coming out of a stabilizing spin, and aiming its main radio antenna at Earth, Rosetta sent a signal to let mission operators know it had survived the most distant part of its journey.

The signal was received by NASA’s Goldstone ground station in California at 18:18 GMT during the first window of opportunity the spacecraft had to communicate with Earth.

The one-way light time on today, January 20, 2014 between Rosetta and Earth was about 44 minutes and 53 seconds over a distance of 807,224,610.74 km. Rosetta was about 9,188,540 km from the comet, closing up at about 800 m/second.

“This was one alarm clock not to hit snooze on, and after a tense day we are absolutely delighted to have our spacecraft awake and back online,” said Jansen.

Comets are considered the primitive building blocks of the Solar System and perhaps may have helped to ‘seed’ Earth with water, or even the ingredients for life. But many fundamental questions about these enigmatic objects remain, and through its comprehensive, in situ study of Comet 67P/Churyumov-Gerasimenko, Rosetta aims to unlock the secrets contained within.

“All other comet missions have been flybys, capturing fleeting moments in the life of these icy treasure chests,” said Taylor. “With Rosetta, we will track the evolution of a comet on a daily basis and for over a year, giving us a unique insight into a comet’s behavior and ultimately helping us to decipher their role in the formation of the Solar System.”

But first, essential health checks on the spacecraft must be completed. Then the eleven instruments on the orbiter and ten on the lander will be turned on and prepared for studying Comet 67P/Churyumov-Gerasimenko.

“We have a busy few months ahead preparing the spacecraft and its instruments for the operational challenges demanded by a lengthy, close-up study of a comet that, until we get there, we know very little about,” says Andrea Accomazzo, Rosetta operations manager.

Rosetta’s first images of 67P/Churyumov-Gerasimenko are expected in May, when the spacecraft is still 2 million km from its target. Towards the end of May, the spacecraft will execute a major maneuver to line up for its critical rendezvous with the comet in August.

After rendezvous, Rosetta will start with two months of extensive mapping of the comet’s surface, and will also make important measurements of the comet’s gravity, mass and shape, and assess its gaseous, dust-laden atmosphere, or coma. The orbiter will also probe the plasma environment and analyse how it interacts with the Sun’s outer atmosphere, the solar wind.

Using these data, scientists will choose a landing site for the mission’s 100 kg Philae probe. The landing is currently scheduled for November 11, 2014 and will be the first time that a landing on a comet has ever been attempted.

With almost negligible gravity from the comet’s 4 km-wide nucleus, Philae will have to use ice screws and harpoons to stop it from rebounding back into space after touchdown.

Among its wide range of scientific measurements, Philae will send back a panorama of its surroundings, as well as very high-resolution pictures of the surface. It will also perform an on-the-spot analysis of the composition of the ices and organic material, including drilling down to 23 cm below the surface and feeding samples to Philae’s on-board laboratory for analysis.

The focus of the mission will then move to the ‘escort’ phase, during which Rosetta will stay alongside the comet as it moves closer to the Sun, monitoring the ever-changing conditions on the surface as the comet warms up and its ices sublimate.

Rosetta will follow the comet throughout the remainder of 2015, as it heads away from the Sun and activity begins to subside.

You can read the team’s blog about the “wake up” here, and find out more about the Rosetta mission here.

Here’s a replay of the acquisition of signal:

Posted on by Fraser Cain

Astronomy Cast Ep. 331: Arthur C. Clarke’s Technologies

In our previous episode, we introduced Arthur C. Clarke, the amazing man and science fiction writer. Today we’ll be discussing his legacy and ideas on space exploration. You’ll be amazed to hear how many of the ideas we take for granted were invented or just accurately predicted by Arthur C. Clarke.
Continue reading “Astronomy Cast Ep. 331: Arthur C. Clarke’s Technologies”

Posted on by David Dickinson

The Moon Occults Saturn in the Dawn this Weekend

Saturn and the waning crescent Moon rising to the SE at about 4 AM local on January 25th, 2014. Created using Stellarium

 Mark your calendars: the first in a series of interesting occultations of Saturn by the Moon for 2014 starts this weekend.

The year 2014 features 11 occultations of the planet Saturn by the Moon, and there are 23 total for 2014 of every planet except Neptune and Jupiter.

An occultation occurs when one foreground celestial object completely obscures another. Technically, a total solar eclipse is an occultation of the Sun by the Moon, although it’s never referred to as such. The term finds modern usage mainly for the blocking of stars and planets by the Moon. Very occasionally, an asteroid or planet can occult a distant star as well.

And yes, the modern astronomical term “occultation” traces its hoary roots back to the days when astronomy was intertwined with the pseudoscience of astrology.  To this day, the term still makes some folks wonder if astronomers are secretly casting horoscopes. Trust us, you’re still on a solid astronomical footing to use the term “occultation.”

Unfortunately, the January 25th occultation of Saturn by the Moon will only grace part of Antarctica, southern Argentina and Chile, and the Falkland Islands post-sunrise. The rest of us still will see a very photogenic pass of Saturn near the waning crescent Moon on the morning of Saturday, January 25th. The Moon will pass just about a degree — two times its apparent width — south of Saturn for northern hemisphere observers.

The footprint for the January 25th occultation of Saturn by the Moon. dashed lines indicate where the events occurs in the daytime sky. (Created using Occult 4.0.11 software)
The footprint for the January 25th occultation of Saturn by the Moon. dashed lines indicate where the events occurs in the daytime sky. (Created using Occult 4.0.11 software)

Both the Moon and Saturn will reside in the astronomical constellation of Libra this weekend during closest passage. The pair will rise around 2 AM local. After their brief tryst, the Moon will head towards New on January 30th while Saturn will continue to rise successively earlier as its heads towards opposition and the start of evening Saturn observing season on May 10th, 2014.

January 2014 is also notable for having two New Moons, an occurrence informally known as a Black Moon. This occurs again this year in March, and February 2014 is devoid of a New Moon. February is the only month that can be “missing a Moon phase” as it’s the only one shorter the synodic period of 29.5 days, in which the Moon returns to like phase.

Saturn as imaged by the author in 2012.
Saturn as imaged by the author in 2012.

In the telescope, Saturn will present a +0.8 magnitude disk 16” across (38” with rings from tip-to-tip). Saturn’s rings are tipped open to our line of sight by about 22 degrees in 2014, and are widening towards a maximum of 27 degrees in 2016 through 2017. If you have an equatorial telescope with tracking capability, it may be possible this weekend to follow Saturn up into the daytime sky. Though Saturn isn’t quite bright enough to see in the daytime unaided, it might just be possible to spy using binoculars on the 25th using the nearby crescent Moon as a guide.  Saturn is a tough daytime target to be sure, but it’s not impossible to acquire with a little skill and patience.

The current cycle of occultations of Saturn began on December 1st, 2013 and ends on November 22nd, 2014. The cycle will move progressively northward through the year.

The Moon and Saturn put on a repeat performance over almost the same exact location (this time in darkness) on April 17th, 2014, and the best event in the cycle for North America will be the August 31st daytime occultation of Saturn by the waxing crescent Moon.

Now for the wow factor of what you’re seeing. On Saturday morning, the Moon is just over 371,000 kilometres distant, or a little over a light second away. Saturn is over four thousand times more remote at just over 10.1 astronomical units (AUs) distant, which works out to 1.5 billion kilometres, or over 83 light minutes away.  And although the Moon is over a 112 times larger in apparent diameter than Saturn as seen from the Earth, the globe of Saturn is actually over 34 times bigger.

Saturn and the Moon crossing the local meridian shortly after sunset on January 25th. Created using Starry Night Education Software.
Saturn and the Moon crossing the local meridian shortly after sunset on January 25th. Created using Starry Night Education Software.

And though we’ve been to the Moon lots since the dawn of the Space Age, only two spacecraft (Voyagers 1 and 2) have made brief flybys of the ringed world, and only one – Cassini – has orbited it. Note that China’s Chang’e-3 lander and rover are about to experience their second sunset this weekend as well from the lunar surface since landing on the Moon last month.

And although lots of planets get occulted by the Moon in 2014, no stars brighter than +1st magnitude lie in its path. In fact, the next cycle of bright star occultations by the Moon doesn’t resume until the Moon meets Aldebaran in January 29th, 2015.

There are, however, over a 100 lesser events involving the Moon occulting naked eye stars worldwide in 2014. Two such events occur this week as well, when the 48% illuminated Moon occults the +4.5th magnitude star Lambda Virginis for west-central South America on the morning of January 24th, and the occultation of the +2.8th magnitude star Alpha Librae  (Zubenelgenubi) for central Asia on January 25th.

Don’t miss these celestial events, and be sure to send those pics in to Universe Today… there’s something for everyone happening in the sky this week worldwide!

Posted on by Nancy Atkinson

Watch Live: ESA Waits for Signal from Comet-Chasing Spacecraft

Rosetta
Rosetta

Watch live streaming video from eurospaceagency at livestream.com

UPDATE: Rosetta woke up! Read our full story about the acquisition of signal here.

For the first time, a spacecraft will follow a comet as it approaches the Sun and land on its nucleus. But today is key to the success of the mission. After nearly two and a half years in hibernation, its time for Rosetta to wake up!

Rosetta has been soaring through the inner solar system for nearly a decade –flying past Mars and Earth several times and even briefly visiting a couple of asteroids. A special ‘hibernation mode’ for the spacecraft was designed by engineers to allow it to survive the large distances from the Sun during its cruise. Since it went into hibernation on June 9, 2011, Rosetta has orbited entirely on its own completely out of contact. But now the Rosetta spacecraft is finally entering the home stretch of its mission to orbit the 4-km-wide comet 67P/Churyumov-Gerasimenko.

Watch live, above, as mission controllers at ESA await for a signal from the spacecraft. The Rosetta mission control team at ESOC is expecting to receive the signal between 17:30-18:30 UTC.
Continue reading “Watch Live: ESA Waits for Signal from Comet-Chasing Spacecraft”

Posted on by Fraser Cain

What Is A Solar Sail?

What Is A Solar Sail?

I’m Fraser Cain, and I’m a sailor. Well, okay, I’ve got a sailboat that I take out on the water when its warm and the weather’s nice here on Vancouver Island. I think it’s one of the reasons I absolutely love the idea of a solar sail.

Here’s how they work: Light is made up of photons. Even though they have no mass at rest, they have momentum when they’re moving, well, light speed. When they reflect off a surface, like a mirror or a shiny piece of metal, they impart some of this momentum to that surface. This effect is negligible here on Earth, but out in space, with forces perfectly in balance, that additional momentum can really add up.

A spacecraft flying to Mars gets pushed off course by several thousand kilometers because of light pressure from the Sun.If mission planners didn’t compensate for this drift, their spacecraft would miss the planet, or even worse, crash into it. Even though the total amount of pressure per square meter on a solar sail is minuscule, it’s constantly streaming from the Sun, and it’s totally free….And propulsion that you don’t have to carry with you is the best kind there is.

This is more than just an idea. Solar sails have already been launched and deployed in space. The Japanese Ikaros satellite unfurled a 14-meter solar sail back in 2010. NASA launched its own Nanosail-D spacecraft in 2011. An even bigger solar sail, the Sunjammer, is planned for launch in 2014. The Planetary Society is working on a solar sail project as well.

The closer to the Sun you are, the better they work. In fact, a solar sail would be an ideal vehicle to explore the regions of Mercury and Venus, since they receive so much radiation. But you’re probably wondering how a solar sail could get down to those planets because light is streaming from the Sun in all directions. It’s all about raising and lowering your orbit. If you want to raise your orbit around an object, all you have to do is speed up. And if you want to lower your orbit, you just need to slow down.

A solar sail launched from Earth would start out with the same orbital velocity around the Sun as the Earth. To get into a higher orbit, it tilts the sail so that the light from the Sun speeds it up. And to get into a lower orbit, it tilts in the opposite direction, and the light from the Sun acts like a brake.

Solar Sail. Image Credit: NASA
Solar Sail. Image Credit: NASA

A solar sail might even be the ideal spacecraft to make the journey to another star. An interstellar solar sail could lower its orbit so that it’s just above the surface of the Sun. Then, it would unfurl the full sail and capture the most possible photons. A series of powerful laser beams would then target the sail and increase its velocity to a significant fraction of the speed of light.

Of course, you’d need a solar sail thousands of kilometers across, made of a material thinner than a human hair, and lasers putting out more energy than all of humanity. The idea is still intriguing, even though it’s well outside our current technology. Once this technology gets better tested, we’ll to see many more missions employ solar sails as part of their propulsion system.