orbit Archives

October 19, 2014December 23, 2015 by Tim Reyes

A Compendium of Universe Today Comet Siding Spring Articles: January 2013 – October 2014

Comet C/2013 A1 Siding Spring passed between the Small Magellanic Cloud (left) and the rich globular cluster NGC 130 on August 29, 2014. Credit: Rolando Ligustri

We present here a compendium of Universe Today articles on comet Siding Spring. Altogether 18 Universe Today stories and counting have represented our on-going coverage of a once in a lifetime event. The articles beginning in February 2013, just days after its discovery, lead to the comet’s penultimate event – the flyby of Mars, October 19, 2014. While comet Siding Spring will reach perihelion just 6 days later, October 25, 2014, it will hardly have sensed the true power and impact that our Sun can have on a comet.

Siding Spring’s Oort Cloud cousin, Comet ISON in November 2013 encountered the Sun at a mere 1.86 million km. The intensity of the Sun’s glare was 12,600 times greater than what Siding Spring will experience in a few days. Comet ISON did not survive its passage around the Sun but Comet Siding Spring will soon turn back and begin a very long journey to its place of origin, the Oort Cloud far beyond Pluto.

An animation of comet Siding Springs passage through the inner Solar System. The scale size of its place of origin would dwarf the orbits of the Solar System to little more than a small dot. (Illustration Credit: Near-Earth Object (NEO) office, NASA/JPL)

The closest approach for comet Siding Spring with the Sun – perihelion is at a distance of 1.39875 Astronomical Units (1 AU being the distance between the Earth and Sun), still 209 million km (130 million miles). The exact period of the comet is not exactly known but it is measured in millions of years. In my childhood astronomy book, it stated that comet Halley, when it is at its furthest distance from the Sun, is moving no faster than a galloping horse. This has also been all that comet Siding Spring could muster for millions of years – the slightest of movement in the direction of the Sun.

It is only in the last 3 years, out all the millions spent on its journey, that it has felt the heat of the Sun and been in proximity to the planetary bodies of our Solar System. This is story of all long period comets. A video camera on Siding Spring would have recorded the emergence and evolution of one primate out of several, one that left the trees to stand on two legs, whose brain grew in size and complexity and has achieved all the technological wonders (and horrors) we know of today.

Now with its close encounter with Mars, the planet’s gravity will bend the trajectory of the comet and reduce its orbital period to approximately one million years. No one will be waiting up late for its next return to the inner Solar System.

It is also unknown what force in the depths of the Oort cloud nudged the comet into its encounter with Mars and the Sun. Like the millions of other Oort cloud objects, Siding Spring has spent its existence – 4.5 Billion years, in the darkness of deep space, with its parent star, the Sun, nothing more than a point of light, the brightest star in its sky. The gravitational force that nudged it may have been a passing star, another cometary body or possibly a larger trans-Neptunian object the size of Pluto and even as large as Mars or the Earth.

The forces of nature on Earth cause a constant turning over geological features. Our oceans and atmosphere are constantly recycling water and gases. The comets that we receive from the Oort Cloud are objects as old as our Solar System. Yet it is the close encounter with Mars that has raised the specter of an otherwise small ordinary comet. All these comets from deep space are fascinating gems nearly unaltered for 1/3rd of the time span of the known Universe.

Universe Today’s Siding Spring Compendium

2014/10/17: Here’s A Look At Comet Siding Spring Two Days Before Its Encounter With Mars

2014/10/17: Weekly Space Hangout Oct 17 2014

2014/10/15: Comet A1 Siding Spring vs Mars Views In Space And Time

2014/10/10: How To See Comet Siding Spring As It Encounters Mars

2014/10/08: Comet Siding Spring Close Call For Mars Wake Up Call For Earth

2014/09/19: How NASA’s Next Mars Spacecraft Will Greet The Red Planet On Sunday

2014/09/09: Tales Tails Of Three Comets

2014/09/05: Maven Mars Orbiter Ideally Poised To Uniquely Map Comet Siding Spring Composition Exclusive Interview With Principal Investigator Bruce Jakosky

2014/08/30: Caterpillar Comet Poses For Pictures En Route To Mars

2014/07/26: NASA Preps For Nail Biting Comet Flyby Of Mars

2014/05/08: Interesting Prospects For Comet A1 Siding Spring Versus The Martian Atmosphere

2014/03/27: Mars Bound Comet Siding Spring Sprouts Multiple Jets

2014/01/29: Neowise Spots Mars Crossing Comet

2014/01/02: Comets Prospects For 2014 A Look Into The Crystal Ball

2013/04/12: New Calculations Effectively Rule Out Comet Impacting Mars In 2014

2013/03/28: NASA Scientists Discuss Potential Comet Impact On Mars

2013/03/05: Update On The Comet That Might Hit Mars

2013/02/26: Is A Comet On A Collision Course With Mars

September 22, 2014December 23, 2015 by Jason Major

MESSENGER Completes Second Burn to Maintain Mercury Orbit

Illustration of MESSENGER in orbit around Mercury (NASA/JPL/APL)

A little over a week before NASA’s MAVEN spacecraft fired its rockets to successfully enter orbit around Mars, MESSENGER performed a little burn of its own – the second of four orbit correction maneuvers (OCMs) that will allow it to remain in orbit around Mercury until next March. Although it is closing in on the end of its operational life it’s nice to know we still have a few more months of images and discoveries from MESSENGER to look forward to!

MESSENGER's orientation after the start of orbit correction maneuver 10 (OCM-10). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington — MESSENGER’s orientation after the start of orbit correction maneuver 10 (OCM-10). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The first OCM burn was performed on June 17, raising MESSENGER’s orbit from 115 kilometers (71.4 miles) to 156.4 kilometers (97.2 miles) above the surface of Mercury. That was the ninth OCM of the MESSENGER mission, and at 11:54 a.m. EDT on Sept. 12, 2014, the tenth was performed.

According to the mission news article:

At the time of this most recent maneuver, MESSENGER was in an orbit with a closest approach of 24.3 kilometers (15.1 miles) above the surface of Mercury. With a velocity change of 8.57 meters per second (19.17 miles per hour), the spacecraft’s four largest monopropellant thrusters (with a small contribution from four of the 12 smallest monopropellant thrusters) nudged the spacecraft to an orbit with a closest approach altitude of 94 kilometers (58.4 miles). This maneuver also increased the spacecraft’s speed relative to Mercury at the maximum distance from Mercury, adding about 3.2 minutes to the spacecraft’s eight-hour, two-minute orbit period.

OCM-10 lasted for 2 1/4 minutes and added 3.2 minutes to the spacecraft’s 8-hour, 2-minute-long orbit. (Source)

The next two burns will occur on October 24 and January 21.

After its two final successful burns MESSENGER will be out of propellant, making any further OCMs impossible. At the planned end of its mission MESSENGER will impact Mercury’s surface in March of 2015.

WATCH: A Tribute to MESSENGER

Built and operated by The Johns Hopkins University Applied Physics Laboratory (JHUAPL), MESSENGER launched from Cape Canaveral Air Force Station on August 3, 2004. It entered orbit around Mercury on March 18, 2011, the first spacecraft ever to do so. Since then it has performed countless observations of our Solar System’s innermost planet and has successfully mapped 100% of its surface. Check out the infographic below showing some of the amazing numbers racked up by MESSENGER since its launch ten years ago, and read more about the MESSENGER mission here.

"MESSENGER by the Numbers" - and infographic by NASA — “MESSENGER by the Numbers” – an infographic by NASA

August 25, 2014December 30, 2015 by Jason Major

Take a Flight Over a Massive Aurora

When we see an auroral arc - and associated rays - we really seeing a small section of the much larger, permanent aurora called the auroral oval. The northern oval is centered over the geomagnetic north pole located in northern Canada. Credit: NASA

Post by Alexander Gerst.

Or perhaps I should say “eine grosse Aurora!” ESA astronaut Alexander Gerst made this time-lapse of a “massive aurora” as seen from the Space Station on August 24. The entire video is beautiful, showing not just a view of the ghostly green aurora but also plenty of stars, airglow, the graceful rotation of the ISS’ solar arrays, and finally the blooming light of dawn – one of sixteen the crew of the Station get to witness every day.

Then again, I’m now wondering: what is the mass of an aurora? Hmm…

Source: ESA on Facebook

June 2, 2014December 23, 2015 by Jason Major

Stunning Snapshots from Space Courtesy of Reid Wiseman

Sunset-lit clouds swirl over Perth on May 31, 2014 (Reid Wiseman/NASA)

On May 28 the crew of Expedition 40/41 launched from Baikonur Cosmodrome, their Soyuz TMA-13M arriving at the International Space Station about eight and a half hours later. And it didn’t take much time for the newly-arrived NASA astronaut Reid Wiseman to start taking photos from his new vantage point in orbit and sharing them on Twitter for the rest of us to enjoy! Here are some of Reid’s latest images from the edge of space, looking down on the beautiful blue world we call home.

One of Reid Wiseman's first few tweets from space — One of Reid Wiseman’s first few tweets from space!

A "beautiful pass over the Falkland Islands" (aka Malvinas) on May 30 with docked Soyuz in the foreground — A “beautiful pass over the Falkland Islands” (aka Islas Malvinas) on May 30 with docked Soyuz in the foreground

Reid confirmed that the Earth is indeed round with a 12mm lens on June 1

Looking down on glacial flows near the Strait of Magellan

Pink clouds at sunset may look beautiful from Earth but "not as pretty here" according to Reid Wiseman — Pink clouds at sunset may look beautiful from Earth but “not as pretty here” according to Reid Wiseman

May 31 was a "nice day to hit the beach" in Santos, Brazil — May 31 was a “nice day to hit the beach” in Santos, Brazil

"Our planet is almost all ocean and so pretty," Tweeted Reid on June 1 — “Our planet is almost all ocean and so pretty,” Tweeted Reid on June 1

A "Soyuz selfie" in the cupola with Expedition 40/41 crew members Alexander Gerst, Oleg Artemyev, and Reid Wiseman, shared on June 2 — A “Soyuz group selfie” in the cupola with Expedition 40/41 crew members Alexander Gerst, Oleg Artemyev, and Reid Wiseman, shared on June 2

"Chile just left me speechless," Reid tweeted on June 4 — “Chile just left me speechless,” Reid tweeted on June 4

"Clouds turn 2D into 3D" tweeted Reid on Thursday, June 5 — “Clouds turn 2D into 3D” tweeted Reid on Thursday, June 5

Just a week into his stay aboard the ISS microgravity is already second nature!

See these photos (and more as they are taken!) on Reid Wiseman’s Twitter feed, and learn more about Expedition 40 here.

Photos courtesy Reid Wiseman/NASA.

May 27, 2014December 23, 2015 by Bob King

Observing Alert – Space Station ‘Marathon’ Starts This Week

Time exposure showing the International Space Station making a bright pass across the northern sky. Credit: Bob King

What’s your favorite satellite? For me it’s the space station. Not only is it the brightest spacecraft in the sky, but it’s regularly visible from so many places. It’s also unique. Most satellites are either spent rocket stages or unmanned science and surveillance probes. The ISS is inhabited by a crew of astronauts. Real people.

Every time I see that bright, moving light I think of the crew floating about the cabin with their microgravity hair, performing experiments and pondering the meaning of it all while gazing out the cupola windows at the rolling blue Earth below. Starting Friday, the station will make up to 5 flybys a night from dusk till dawn. Marathon anyone?

The ISS’s orbit is inclined 51.6 degrees to the equator and passes overhead for anyone living between 51.6 degrees north and 51.6 degrees south latitude. It’s visible well beyond this zone also but never passes through the zenith outside of these limits. Traveling at a little more than 17,000 mph (27,350 kph) the station completes an orbit in 93 minutes.

Diagram showing the Earth in late May when the space station's orbital track is closely aligned with the day-night terminator. The astronauts see the sun 24-hours a day (midnight sun effect) while we on the ground get to watch repeated passes. Credit: Bob King — Diagram showing the Earth in late May when the space station’s orbital track is closely aligned with the day-night terminator. The astronauts see the sun 24-hours a day (midnight sun effect) while we on the ground get to watch repeated passes. Credit: Bob King

Most of the time we get one easy-to-see bright pass preceded or followed by a fainter partial pass. ‘Partials’ occur when the space station glides into Earth’s shadow and disappears from view during an appearance. But in late May-early June each year, the space station’s orbit and Earth’s day-night terminator nearly align. From the astronauts’ viewpoint, the sun never sets, much like seeing the midnight sun from the Arctic Circle. From down on the planet between latitudes 40-55 degrees north, the ISS remains in sunlight during repeated 90 minute-long orbits.

Instead of once or twice a night, we’ll see passes all night long from dusk till dawn starting about May 30. For instance, on May 31 from Minneapolis, Minn., skywatchers will be treated to four flybys at 12:12 a.m, 1:44 a.m., 3:20 a.m. and 11:23 p.m. The best nights are June 4 and 6 with five passes. By the 10th, the space station ‘marathon’ winds down and we return to 2-3 passes a night.

In late May-early June near the summer solstice, the sun doesn’t set on the International Space Station

The ISS always appears in the western sky first and travels east opposite to the movement of the stars. Low altitude flybys are fainter because there’s more lateral distance between you and the station. Even then the it still shines as bright as Vega. But when the ISS flies overhead, it’s only about 250 miles away, as close as it gets. Then it outshines everything in the night sky except Venus and the moon. Absolutely stunning.

The track of the ISS near Vega in Lyra. From right to left, the station is passing from sunlight into Earth's shadow. Its color transitions from white to red. Credit: Bob King — The track of the ISS near Vega in Lyra. From right to left, the station is passing from sunlight into Earth’s shadow. Its color transitions from white to red. Credit: Bob King

Have you ever noticed that satellites, including the ISS, appear to move in a jerky or zigzag fashion if you watch them closely? What you’re really are your own eyes not moving smoothly as you follow the satellite across the starry sky. My favorite passes are those where the space station fades away mid-flyby as it encounters Earth’s shadow. I always keep binoculars handy for these passes so I can watch the ISS turn color from pale yellow (caused by the gold Mylar plastic used in its many solar panels) to orange and red as it experiences one of its many orbital sunsets.

The phenomenon is easy to capture on camera too. Find out when the station will cross into shadow using the maps from Heavens-Above (see below) and point your tripod-mounted camera in that direction. I typically use a 35mm lens wide open to f/2.8 and a 30-second exposure at either ISO 400 – if still twilight – or 800 in a darker sky.

The multiple solar panels on the ISS give it the shape of the letter ‘H’ when viewed through a telescope. Other modules are visible too but hard to see as clearly. Credit: NASA

There are many ways to find out when the ISS will pass over your city. My favorite are the listings in Heavens-Above. Login with your city and you’ll see a complete list with links to create maps of the station’s track across the sky. There’s also Spaceweather’s Satellite Flyby tracker. Type in your zip code and hit enter. Couldn’t be easier. You can also have NASA send you an e-mail when the most favorable (highest, brightest) passes occur by adding your e-mail to the Spot the Station site. Be aware though that you won’t be notified of some of the less favorable passes.

Half-minute video of the space station tracked through a telescope

One last pleasure of space station watching is seeing it in a telescope. Notoriously tricky to track when magnified, after minimal research I’ve come up with a method that allows at least a half dozen people to see it up close during a good flyby. One person mans the finderscope, keeping the station in the center of the crosshairs, while one happy observer after another takes their turn for a look through the eyepiece. Sure, it’s a little herky-jerky, but you’d be surprised how much you can see at magnifications as low as 60x. The solar panels really jump out. Observing solo might mean a couple tries positioning the moving target ahead of where you think it will cross the field of view and then being ready to lock on and follow.

Well, I’m going to prep for the upcoming marathon. See you in spirit on the course!

May 19, 2014December 23, 2015 by Jason Major

Space Station’s Veggies Are “Grow” to Launch

Expedition 39 flight engineer Steve Swanson activates the Veg-01 experiment (NASA/Koichi Wakata)

In what could become the world’s first orbiting salad bar, NASA’s Veggie experiment was initiated on May 8 after a successful (if slightly delayed) launch to the Space Station on Friday, April 18 aboard a SpaceX Dragon capsule. In development for several years, the LED-powered plant growth experiment is finally getting the chance to put down its roots.

After receiving the experiment on Sunday, April 20, Expedition 39 astronauts Rick Mastracchio and Steve Swanson installed the Veg-01 unit inside ESA’s Columbus module on May 7. The next day Veg-01 was turned on, with a root mat and six small pillows containing “Outredgeous” romaine lettuce seeds within a special fertilized clay inserted inside its collapsible Teflon bellows.

The inside of the Veg-01 unit aboard the ISS (Source)

The lettuce plants are scheduled to grow for 28 days, during which time they will be periodically photographed, watered, and tested for any microbial growth. The pillows will be thinned down to one plant each, and after the experiment is over the remaining lettuce leaves will be harvested and frozen to be returned to Earth aboard another Dragon capsule later this year. There they’ll be tested and compared with the results of an identical Veggie experiment that’s being conducted at the same time at Kennedy Space Center.

If all goes well, the lettuce will be found to be safe for astronauts to eat. While they await the results, the next experiment can be started.

“My hopes are that Veggie will eventually enable the crew to regularly grow and consume fresh vegetables,” said Dr. Gioia Massa, the NASA science team lead for Veggie.

In addition to providing healthy food, having living plants to care for could be therapeutic for astronauts on long-duration missions in low-Earth orbit and beyond. (Let’s just hope it doesn’t one day end up like Silent Running!)

The Veggie system was developed for NASA by Orbital Technologies Corporation (ORBITEC) in Madison, Wisconsin, via a Small Business Innovative Research Program. Its innovations may eventually lead to better food production not only in space but also in limited-resource regions on Earth. Learn more about the Veg-01 experiment in my previous article here.

Source/more info: NASA news release (Also, see some photos of Veg-01 installed on the ISS here.)

May 15, 2014December 23, 2015 by Jason Major

Mercury’s Ready For Its Close-Up, Mr. MESSENGER

One of the highest-resolution images of Mercury's surface ever acquired.

Are you ready for a good close look at Mercury? At an incredible 5 meters per pixel, this is one of the highest-resolution images of Mercury’s surface ever captured. It was acquired on March 15 with the MESSENGER spacecraft’s MDIS (Mercury Dual Imaging System) instrument and shows an 8.3-km (5.2-mile) -wide section of Mercury’s north polar region, speckled with small craters and softly rolling hills.

Because MESSENGER was moving so quickly relative to the targeted area it was imaging, a short exposure time was necessary to avoid blurring. As a result the image appears a bit grainy. See the original map projection here.

Wondering what the next-best image was of Mercury? Find out below:

The previous record for most extreme close-up of Mercury was held by this image:

7 meter/pixel targeted observation of Mercury by the MESSENGER spacecraft

It was acquired as a targeted observation by MESSENGER’s Narrow-Angle Camera on April 30, 2012, and has a resolution of 7 meters/pixel. It shows an impact melt-covered area about 11 km (7 miles) across near Gaugin crater.

(Although Mercury’s surface may at first appear strikingly similar to the Moon’s, it’s been known since the Mariner 10 mission that the two worlds are very different at fundamental geologic and compositional levels. Read more on that here.)

Images like these are extremely special; during the first two years of MESSENGER’s mission in orbit around Mercury, over 150,000 images were acquired but only five images had resolutions better than 10 meters per pixel.

Artist's impression of MESSENGER orbiting Mercury — Artist’s impression of MESSENGER orbiting Mercury

On April 20, 2014, MESSENGER completed its 3,000th orbit of Mercury (3,075 to date) and is steadily moving into an even lower-altitude orbit. MESSENGER now comes within less than 200 km (124 miles) of the planet’s surface when it passes over its north pole every eight hours… that’s less than half the altitude of the Space Station!

Orbiting at such a low altitude and so often will allow MESSENGER to examine Mercury’s surface in unprecedented detail. Now that 100% of the planet has been successfully mapped by MESSENGER it can spend its second — and last — extended mission investigating specific scientific targets.

Watch: A Tribute to MESSENGER

“The final year of MESSENGER’s orbital operations will be an entirely new mission,” said Sean Solomon, Principal Investigator for MESSENGER. “With each orbit, our images, our surface compositional measurements, and our observations of the planet’s magnetic and gravity fields will be higher in resolution than ever before. We will be able to characterize Mercury’s near-surface particle environment for the first time. Mercury has stubbornly held on to many of its secrets, but many will at last be revealed.”

Read more in a recent news release from the MESSENGER team here.

Want to explore a high-res map of Mercury and see where MESSENGER is right now? Click here.

Image credits: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

May 9, 2014December 23, 2015 by Bob King

Observing Alert: See Mercury’s Best Evening Show of the Year

Mercury starts its best period of visibility in the evening sky for skywatchers at mid-northern latitudes this weekend. This map shows the sky facing northwest about 40 minutes after sundown. Bright Jupiter also provides a convenient sightline for locating Mercury. Stellarium

Don’t let furtive Mercury slip through your fingers this spring. The next two and a half weeks will be the best time this year for observers north of the tropics to spot the sun-hugging planet. If you’ve never seen Mercury, you might be surprised how bright it can be. This is especially true early in its apparition when the planet looks like a miniature ‘full moon’.

Mercury, like Venus, displays phases as it revolves around the sun as seen from Earth's perspective outside Mercury's orbit. Credit: Bob King — Mercury, like Venus, displays phases as it revolves around the sun as seen from Earth’s perspective outside Mercury’s orbit. Both Mercury and Venus appear largest when nearly lined up between Earth and sun at inferior conjunction. Planets not to scale and phases shown are approximate. Credit: Bob King

Both Venus and Mercury pass through phases identical to those of the moon. When between us and the sun, Mercury’s a thin crescent, when off to one side, a ‘half-moon’ and when on the far side of the sun, a full moon. This apparition of the planet is excellent because Mercury’s path it steeply tilted to the horizon in mid-spring.

We start the weekend with Mercury nearly full and brighter than the star Arcturus. Twilight tempers its radiance, but :

* Find a location with a wide open view to the northwest as far down to the horizon as possible.

* Click HERE to get your sunset time and begin looking for the planet about 30-40 minutes after sunset in the direction of the sunset afterglow.

* Reach your arm out to the northwestern horizon and look a little more than one vertically-held fist (10-12 degrees) above it for a singular, star-like object. Found it? Congratulations – that’s Mercury!

* No luck? Start with binoculars instead and sweep the bright sunset glow until you find Mercury. Once you know exactly where to look, lower the binoculars from your eyes and you should see the planet without optical aid. And before I forget – be sure to focus the binoculars on a distant object like a cloud or the moon before beginning your sweeps. I guarantee you won’t find Mercury if it’s out of focus.

Through a telescope, Mercury looks like a gibbous moon right now but its phase will lessen as it moves farther to the ‘left’ or east of the sun. Greatest eastern elongation happens on May 24. On and around that date the planet will be farthest from the sun, standing 12-14 degrees high 40 minutes after sundown from most mid-northern locales.

jjjjjjj — Mercury is even better placed on May 19 but fades and begins to drop back down toward the horizon late in the month. Stellarium

The planet fades in late May and become difficult to see by early June. Inferior conjunction, when Mercury passes between the Earth and sun, occurs on June 19. Unlike Venus, which remains brilliant right up through its crescent phase, Mercury loses so much reflective surface area as a crescent that it fades to magnitude +3. Its greater distance from Earth, lack of reflective clouds and smaller size can’t compete with closer, brighter and bigger Venus.

Mercury's path across the solar disk as seen from the Solar and Heliospheric Observatory (SOHO) on November 8, 2006. The transit was visible in eastern Europe and the eastern hemisphere. Credit: NASA. — When a planet crosses the disk of the sun it’s called a transit. Mercury’s path across the solar disk is seen from the Solar and Heliospheric Observatory (SOHO) on November 8, 2006. Credit: NASA.

Mercury’s 7-degree inclined orbit means it typically glides well above or below the sun’s disk at inferior conjunction. But anywhere from 3 up to 13 years in either November or May the planet passes directly between the Earth and sun at inferior conjunction and we witness a transit. This last happened for U.S. observers on Nov. 8, 2006; the next transit occurs exactly two years from today on May 9, 2016. That event will be widely visible across the Americas, Western Europe and Africa. After having so much fun watching the June 2012 transit of Venus I can’t wait.

May 8, 2014December 23, 2015 by Bob King

Asteroid 2013 UQ4 Suddenly Becomes a Dark Comet with a Bright Future

Comet C/2013 UQ4, once thought to be an asteroid, now shows characteristics of a comet including a coma. This photo was made on May 7, 2014. Credit: Artyom Novichonok and Taras Prystavski

On October 23, 2013, astronomers with the Catalina Sky Survey picked up a very faint asteroid with an unusual orbit more like a that of a comet than an asteroid. At the time 2013 UQ4 was little more than a stellar point with no evidence of a hazy coma or tail that would tag it as a comet. But when it recently reappeared in the morning sky after a late January conjunction with the sun, amateur astronomers got a surprise.

On May 7, Comet ISON co-discoverer Artyom Novichonok, and Taras Prystavski used a remote telescope located in Siding Spring, Australia to take photos of 2013 UQ4 shortly before dawn in the constellation Cetus. Surprise, surprise. The asteroid had grown a little fuzz, making the move to comethood. No longer a starlike object, 2013 UQ4 now displays a substantial coma or atmosphere about 1.5 arc minutes across with a more compact inner coma measuring 25 arc seconds in diameter. No tail is visible yet, and while its overall magnitude of +13.5 won’t make you break out the bottle of champagne, it’s still bright enough to see in a 12-inch telescope under dark skies.

Wide field map showing the comet's movement from Cetus through Pisces and into Cepheus in July when it becomes circumpolar for skywatchers at mid-northern latitudes. It should reach peak brightness of 7th magnitude in early July. Created with Chris Marriott's SkyMap program — Wide field map showing the comet’s movement from Cetus through Pisces and into Cepheus in July when it becomes circumpolar for skywatchers at mid-northern latitudes. It should reach a peak brightness of 7th magnitude in early July. Click to enlarge. Created with Chris Marriott’s SkyMap program

The best is yet to come. Assuming the now renamed C/2013 UQ4 continues to spout dust and water vapor, it should brighten to magnitude +11 by month’s end as it moves northward across Pisces and into a dark morning sky. Perihelion occurs on June 5 with the comet reaching magnitude +8-9 by month’s end. Peak brightness of 7th magnitude is expected during its close approach of Earth on July 10 at 29 million miles (46.7 million km).

This should be a great summer comet, plainly visible in binoculars from a dark sky as it speeds across Cepheus and Draco during convenient viewing hours at the rate of some 7 degrees per night! That’s 1/3 of a degree per hour or fast enough to see movement through a telescope in a matter of minutes when the comet is nearest Earth.

Lightcurve showing the date on the bottom and magnitude along the vertical. Work by Artyom Novichonok and Taras Prystavski — Light curve showing C/2013 UQ4 brightening to a sharp peak in early July and then quickly fading. Created by Artyom Novichonok and Taras Prystavski

Come August, C/2013 UQ4 rapidly fades to magnitude +10 and then goes the way of so many comets – a return to a more sedentary lifestyle in the cold bones of deep space.

C/2013 UQ4 belongs to a special category of asteroids called damocloids (named for asteroid 5335 Damocles) that have orbits resembling the Halley-family comets with long periods, fairly steep inclinations and highly eccentric orbits (elongated shapes). Some, like Comet Halley itself, even travel backwards as they orbit the sun, an orbit astronomers describe as ‘retrograde’.

Evolution of a comet as it orbits the sun. Credit: Laboratory for Atmospheric and Space Sciences/ NASA

Damocloids are thought to be comets that have lost all their fizz. With their volatile ices spent from previous trips around the sun, they stop growing comas and tails and appear identical to asteroids. Occasionally, one comes back to life. It’s happened in at least four other cases and appears to be happening with C/2013 UQ4 as well.

Studies of the comet/asteroid’s light indicate that UQ4 is a very dark but rather large object some 4-9 miles (7-15 km) across. It’s estimated that C/2013 UQ4 takes at least 500 years to make one spin around the sun. Count yourself lucky this damocloid decided to spend its summer vacation in Earth’s skies. We’ll have more detailed maps and updates as the comet becomes more easily visible next month. Stay tuned.

January 21, 2014December 30, 2015 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?”