Artist's conception of Mars, with asteroids nearby. Credit: NASA
Here’s a finding to give planetary protectionists pause: two species of spores mounted on the International Space Station’s hull a few years back showed a high survival rate after 18 months in space.
Providing that they are shielded against solar radiation, it appears the spores are quite hardy and could easily transport on a spacecraft headed for Mars — which is concerning since so many scientific investigations there these days are focused on habitability of Martian life (whether past or present). The experiment was published in 2012, but highlighted in a recent NASA press release about planetary protection.
The experiment was called PROTECT (an acronym of Resistance of spacecraft isolates to outer space for planetary protection purposes) and studied spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032. B. pumilus spores were found in an air lock between a “clean room” and entrance floor at NASA’s Jet Propulsion Laboratory, and in previous studies were shown to be more resistant to UV radiation and hydrogen peroxide than “wild” strains. B. subtilis is a spore that has been studied in other space environment experiments.
Samples of both spores were mounted on the EXPOSE-E facility on the space station, which provides up to two years of space exposure. The major goal of this European Space Agency experiment is to study “the origin, evolution and distribution of life in the universe,” NASA states, adding that anything mounted outside of there has to survive “cosmic radiation, vacuum, full-spectrum solar light including UV-C, freezing/thawing cycles [and] microgravity.”
The European Technology Exposure Facility (EuTEF) attached to the Columbus module of the International Space Station. Credit: DLR, Institute of Aerospace Medicine/Dr. Gerda Horneck
The experiment found that if the spores were in areas replete with solar UV radiation, most of them were killed. If those rays were filtered out, however, the spores showed a 50 percent survival rate on both space and simulated “Mars” conditions. It is most concerning to scientists when considering a situation where spores could be hiding underneath each other during a spacecraft trip. The ones on the outside would likely die, but the ones on the inside — shielded from solar radiation — could make it there.
One key limitation in this study, however, is that only two types of spores were studied. This does present a case for doing more studies on this matter in the future, however. Space agencies are quite aware of the problem of planetary protection, as evidenced by departments such as NASA’s Office of Planetary Protection and ESA’s Planetary Protection Officer.
Spacecraft designers constantly make decisions to keep the extraterrestrial bodies we study as safe from Earth contamination as possible; one famous example was when the Galileo probe was deliberately sent into Jupiter in 2003 to protect Europa and other potentially life-bearing moons of the giant planet from possible contamination.
Images of Bacillus pumilus SAFR-032 spores (seen in an electron micrograph) on aluminum before and after being exposed to space on an International Space Station experiment. Credit: P. Vaishampayan, et al./Astrobiology
The rock study (led by Tuscia University’s Silvano Onofri) takes the question of the spores in a different direction, which is examining the phenomenon of “lithopanspermia” — how organisms might move between planets (say, on a meteor). Since Mars meteorites have been found on Earth, some researchers have wondered if life could have spread between our two planets. If that were to happen, the researchers cautioned, the spores would have to survive for thousands or millions of years.
The other B. pumilus paper (led by NASA’s Parag A. Vaishampayan) noted that those spores mounted outside of the space station that survived, showed higher concentrations of proteins that could be linked to resisting UV radiation.
Location chart for HD 162826, considered a sibling to the sun. Credit: Ivan Ramirez/Tim Jones/McDonald Observatory
Peer about 110 light-years away from our solar system, and you might catch a glimpse of how our own neighborhood came together. The recent discovery that HD 162826 — a star bright enough to be seen in binoculars — could be a “sibling” of our sun could shed more light on the solar system’s formation, astronomers said.
“We want to know where we were born,” stated Ivan Ramirez, an astronomer at the University of Texas at Austin who led the research. “If we can figure out in what part of the galaxy the sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here.”
The star is called a “sibling” because it could have formed from the same gas and dust cloud in which our own solar system was formed, some 4.5 billion years ago. Since life is in our own solar system, a natural next question is whether HD 162826 could also have life-bearing planets. There is a tiny reason for “yes”, the astronomers said.
Basically, the argument goes that when the stars were first born and close together, chunks of matter could have been knocked off protoplanets and travelled between the two solar systems. There’s a small chance that this could have brought primitive life to Earth, although of course there’s a long way to go before that could even be proved.
This artist’s conception shows a newly formed star surrounded by a swirling protoplanetary disk of dust and gas. Credit: University of Copenhagen/Lars Buchhave
That said, no planets have yet been found around HD 162826. (The star was known before, but just recently identified as a “sibling.”) Separate studies by the University of Texas and University of South Wales said there are likely no “hot Jupiters” (Jupiter-sized planets close to the star) nor Jupiter-sized planet in the solar system even further away. Smaller terrestrial planets, however, would have escaped the notice of this particular study.
The star is about 15 percent more massive than our sun and was selected from a list of 30 candidates based on its chemistry and orbit. There could also be more siblings out there to find, with one potential big help coming soon: the Gaia survey from the European Space Agency launched in December, which will chart the Milky Way in three dimensions.
Because Gaia will showcase the distance and motions of a billion stars, this will allow astronomers to look for these “solar siblings” as far in as the galaxy’s center, increasing the number of stars studied by a factor of 10,000. The exciting thing, the astronomers add, is with enough stars pinpointed as siblings to our sun, their orbits can then be traced back to the origin point — showing the location in the cosmos where the sun first came to be.
More information will be available in the June 1 issue of the Astrophysical Journal. A preprint version is available on Arxiv.
Chris Ferguson, last Space Shuttle Atlantis commander, tests the Boeing CST-100 capsule which may fly US astronauts to the International Space Station in 2017. Ferguson is now Boeing’s director of Crew and Mission Operations for the Commercial Crew Program vying for NASA funding. Credit: NASA/Boeing
KENNEDY SPACE CENTER, FL – Boeing expects to launch the first unmanned test flight of their commercial CST-100 manned ‘space taxi’ in “early 2017,” said Chris Ferguson, commander of NASA’s final shuttle flight in an exclusive one-on-one interview with Universe Today for an inside look at Boeing’s space efforts. Ferguson is now spearheading Boeing’s human spaceflight capsule project as director of Crew and Mission Operations.
“The first unmanned orbital test flight is planned in January 2017 … and may go to the station,” Ferguson told me during a wide ranging, in depth discussion about a variety of human spaceflight topics and Boeing’s ambitious plans for their privately developed CST-100 human rated spaceship – with a little help from NASA.
Boeing has reserved a launch slot at Cape Canaveral with United Launch Alliance (ULA), but the details are not yet public.
If all goes well, the maiden CST-100 orbital test flight with humans would follow around mid-2017.
“The first manned test could happen by the end of summer 2017 with a two person crew,” he said.
Boeing is among a trio of American aerospace firms, including SpaceX and Sierra Nevada Corp, vying to restore America’s capability to fly humans to Earth orbit and the space station by late 2017, using seed money from NASA’s Commercial Crew Program (CCP) in a public/private partnership. The next round of contracts will be awarded by NASA about late summer 2014.
That’s a feat that America hasn’t accomplished in nearly three years.
“It’s been over 1000 days and counting since we landed [on STS-135],” Ferguson noted with some sadness as he checked the daily counter on his watch. He is a veteran of three space flights.
Boeing CST-100 commercial crew capsule approaches the ISS in this artist’s concept. Credit: Boeing
Since the shuttles retirement in July 2011 following touchdown of Space Shuttle Atlantis on the last shuttle flight (STS-135) with Ferguson in command, no American astronauts have launched to space from American soil on American rockets and spaceships.
The only ticket to the ISS and back has been aboard the Russian Soyuz capsule.
Chris and the Boeing team hope to change the situation soon. They are chomping at the bits to get Americas back into space from US soil and provide reliable and cost-effective US access to destinations in low Earth orbit like the ISS and the proposed private Bigelow space station.
Boeing wants to send its new private spaceship all the way to the space station starting on the very first unmanned and manned test flights currently slated for 2017, according to Ferguson.
“NASA wants us to provide [crew flight] services by November 2017,” said Ferguson, according to the terms of the CCP contact award.”
The Boeing CST-100 crew capsule awaits liftoff aboard an Atlas V launch vehicle at Cape Canaveral in this artist’s concept. Credit: Boeing
The CST-100 will launch atop a man rated Atlas V rocket and carry a mix of cargo and up to seven crew members to the ISS.
“So both the first unmanned and manned test flight will be in 2017. The first unmanned orbital flight test is currently set for January 2017. The first manned test could be end of summer 2017,” he stated.
I asked Chris to outline the mission plans for both flights.
“Our first flight, the CST-100 Orbital Flight Test – is scheduled to be unmanned.”
“Originally it was just going to be an on orbital test of the systems, with perhaps a close approach to the space station. But we haven’t precluded our ability to dock.
“So if our systems mature as we anticipate then we may go all the way and actually dock at station. We’re not sure yet,” he said.
So I asked whether he thinks the CST-100 will also go dock at the ISS on the first manned test flight?
“Yes. Absolutely. We want go to all the way to the space station,” Ferguson emphatically told me.
“For the 1st manned test flight, we want to dock at the space station and maybe spend a couple weeks there.”
“SpaceX did it [docking]. So we think we can too.”
“The question is can we make the owners of the space station comfortable with what we are doing. That’s what it really comes down to.”
“As the next year progresses and the design matures and it becomes more refined and we understand our own capability, and NASA understands our capabilities as the space station program gets more involved – then I’m sure they will put the same rigor into our plan as they did into the SpaceX and Orbital Sciences plans.”
“When SpaceX and Orbital [wanted to] come up for the grapple [rather than just rendezvous], NASA asked ‘Are these guys ready?’ That’s what NASA will ask us.”
“And if we [Boeing] are ready, then we’ll go dock at the station with our CST-100.”
“And if we’re not ready, then we’ll wait another flight and go to the station the next time. It’s just that simple.”
“We looked at it and this is something we can do.”
“There are a lot of ways we have to make NASA and ourselves happy. But as a company we feel we can go do it,” Ferguson stated.
Boeing CST-100 crew vehicle docks at the ISS. Credit: Boeing
So the future looks promising.
But the schedule depends entirely on NASA funding levels approved by Congress. And that vital funding has been rather short on supply. It has already caused significant delays to the start of the space taxi missions for all three companies contending for NASA’s commercial crew contracts because of the significant slashes to the agency’s CCP budget request, year after year.
In fact the schedule has slipped already 18 months to the right compared to barely a few years ago.
So I asked Chris to discuss the CCP funding cuts and resulting postponements – which significantly affected schedules for Boeing, SpaceX and Sierra Nevada.
Here it is in a nutshell.
“No Bucks, No Buck Rogers,” explained Ferguson.
“The original plan was to conduct both the unmanned and manned CST-100 test flights in 2015.”
“Originally, we would have flown the unmanned orbital test in the summer of 2015. The crewed test would have been at the end of 2015.”
“So both flights are now a full year and a half later.” Ferguson confirmed.
“For the presidents [CCP] funding requests for the past few years of roughly about $800 million, they [Congress] only approved about half. It was significantly less than the request.”
Now at this very moment Congress is deliberating NASA’s Fiscal 2015 budget.
NASA Administrator Charles Bolden has said he will beg Congress to approve full funding for the commercial crew program this year – on his hands and knees if necessary. NASA’s final shuttle crew on STS-135 mission greets the media and shuttle workers during Atlantis rollover from the OPF-1 processing hanger to the VAB at KSC during May 2011. From left: Rex Walheim, Shuttle Commander Christopher Ferguson, Douglas Hurley and Sandra Magnus. The all veteran crew will delivered the Raffaello multipurpose logistics module (MPLM), science supplies, provisions and space parts to the International Space Station (ISS). Credit: Ken Kremer – kenkremer.com
Otherwise there will be further delays to the start of the space taxi missions. And the direct consequence is NASA would be forced to continue buying US astronaut rides from the Russians at $70 Million per seat. All against the backdrop of Russian actions in the Ukraine where deadly clashes potentially threaten US access to the ISS in a worst case scenario if the ongoing events spin even further out of control and the West ratchets up economic sanctions against Russia.
The CST-100 is designed to be a “simple ride up to and back from space,” Ferguson emphasized to me.
NASA’s 135th and final shuttle mission takes flight on July 8, 2011 at 11:29 a.m. from the Kennedy Space Center in Florida bound for the ISS and the high frontier with Chris Ferguson as Space Shuttle Commander. Credit: Ken Kremer/kenkremer.com
It is being designed at Boeing’s Houston Product Support Center in Texas.
In Part 2 of my interview, Chris Ferguson will discuss the details about the design, how and where the CST-100 capsule will be manufactured at a newly renovated, former space shuttle facility at NASA’s Kennedy Space Center in Florida.
Stay tuned here for Ken’s continuing Boeing, SpaceX, Orbital Sciences, commercial space, Orion, Curiosity, Mars rover, MAVEN, MOM and more planetary and human spaceflight news.
STS-135 Shuttle Commander Chris Ferguson (right) and Ken Kremer (Universe Today) meet at emergency M-113 Tank Practice during crew pre-launch events at the Kennedy Space Center in the weeks before Atlantis July 8, 2011 liftoff. Credit: Ken Kremer- kenkremer.comScale models of NASA’s Commercial Crew program vehicles and launchers; Boeing CST-100, Sierra Nevada Dream Chaser, SpaceX Dragon. Credit: Ken Kremer/kenkremer.com
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. 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.
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.
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 VenusI can’t wait.
British planetary scientist Colin Pillinger with the Beagle 2 lander.
British planetary scientist Colin Pillinger has passed away. Pillinger, age 70, was best known as leading the 2003 attempt to land the Beagle 2 spacecraft on Mars, part of the European Space Agency’s Mars Express mission.
His family said in a statement: “It is with profound sadness that we are telling friends and colleagues that Colin, whilst sitting in the garden yesterday afternoon, suffered a severe brain hemorrhage resulting in a deep coma. He died peacefully this afternoon at Addenbrooke’s hospital, Cambridge, without regaining consciousness … We ask that all respect our privacy at this devastating and unbelievable time.”
While the Beagle 2 spacecraft failed and likely crashed on Mars, the mission was notable because it was the first time an individual researcher had sent their own vessel into space and the first British-built interplanetary spacecraft. However, a lack of funding meant the Beagle 2 project always struggled. The spacecraft did launch, but all contact with Beagle 2 was lost after its separation from the Mars Express spacecraft, just six days before atmospheric entry.
However, the BBC noted that the mission was “a turning point in bringing together the space science and industrial communities in the UK – which didn’t used to speak with one voice. Beagle-2 wasn’t built in Colin’s backyard: it was the product of UK brains and hard-work in many companies and universities.”
Porters at Mt. Bromo in Indonesia warm themselves by a fire as an Eta Aquarid meteor streaks overhead on May 6, 2014. Credit and copyright: Justin Ng.
The Eta Aquarid meteor shower has graced the skies this week and while this hasn’t been an exceptionally active shower, here are a few beautiful photos we’ve received. Above astrophotographer Justin Ng climbed Mount Bromo in Indonesia on May 6, and had to contend with interference from the active volcano.
“After having visited Mt. Bromo several times over the past two years, I must say it’s definitely much more active now and part of the night sky was obscured by the sulphur dioxide gas emitted from Mount Bromo when I took this shot,” Justin said via email. “At times, I was ‘consumed’ by the sulphur gas for several minutes due to the occasional change in wind direction and I could hardly breathe or kept my eyes opened when that happened. Despite these challenging shooting and viewing conditions, the natives or tourists will still ascend the steep stone staircase (approximately 253 concrete steps) that leads to the brim of the steaming, sulphurous, gaping caldera to catch a glimpse of the scenic sunrise every morning.”
Wow! This beautiful image is a result of stacking 4 images taken at different times facing at the same direction.
An Eta Aquarid meteor streaks out of Aquarius at left toward the Milky Way at right. Note the chnages in colour as the meteor travels from left to right and descends into our atmosphere, as seen from Arizona on the night of May 4/5, 2014. Credit and copyright: Alan Dyer/Amazing Sky Photography.A lone Eta Aquarid meteor during the night of May 5, 2014. Credit and copyright: Astro Guillaume on Flickr.
This image is an example of how sparse this meteor shower was this year. “After 547 shots during the night of 5, May 2014 before dawn, my camera has captured only one meteor from the Eta Aquarids meteor Shower!” wrote Astro Guillaume on Flickr.
Inbound: the Hubble Space Telescope images Comet 2013 A1 Siding Spring with its Wide Field Camera 3. Credit: NASA.
It may be the chance of a lifetime for planetary science.
This October, a comet will brush past a planet, giving scientists a chance to study how it possibly interacts with a planetary atmosphere.
The comet is C/2013 A1 Siding Spring, and the planet in question Mars. And although an impact of the comet on the surface of the Red Planet has long been ruled out, a paper in the May 2014 issue of Icarus raises the interesting possibility of possible interactions of the coma of A1 Siding Spring and the tenuous atmosphere of Mars. The study comes out of the Department of Planetary Sciences at the University of Arizona, the Belgian Institute for Space Aeronomy, the Institut de Planétologie et d’Astrophysique de Grenoble at the Université J. Fourier in France, and the Cooperative Institute for Research in Environmental Sciences at the University of Colorado in Boulder.
For the study, researchers considered how active Comet A1 Siding Spring may be at the time of closest approach on October 19th, 2014.
Discovered early last year by Robert McNaught from the Siding Spring Observatory in Australia, Comet A1 Siding Spring created a stir in the astronomical community when it was found that it will passextremely close to Mars later this year. Further measurements of its orbit have since ruled this possibility out, but its passage will still be a close one, with a nominal passage of 138,000 kilometres from Mars. That’s about one third the distance from Earth to the Moon, and 17 times closer than the nearest recorded passage of a comet to the Earth, Comet D/1770 L1 Lexell in 1780. Mars’ outer moon Deimos has an orbital distance of about 23,500 kilometres.
The passage of Comet 2013 A1 Siding Spring through the inner solar system. Credit: NASA.
And although the nucleus will safely pass Mars, the brush with its extended atmosphere might just be detectable by the fleet of spacecraft and rovers in service around Mars. At a distance of 1.4 Astronomical Units (A.U.) from the Sun during the encounter, the vast coma is expected to be comprised primarily of H2O. At an input angle of about 60 degrees, penetration was calculated in the study to impinge down and altitude of 154 kilometres to the topside of the Martian ionosphere, in the middle of the thermosphere.
Such an effect should linger for just over 4 hours, well over the interaction period of Mars’ atmosphere with the coma of just over an hour, centered on 18:30 UT on October 19th, 2014.
What kind of views might missions like HiRISE and MSL get of the comet remains to be seen, although NEOWISE and Hubble are already monitoring the comet for enhanced activity. The Opportunity rover is also still functioning, and Mars Odyssey and ESA’s Mars Express are still in orbit around the Red Planet and sending back data. But perhaps the most interesting possibilities for observations of the event are still en route: India’s Mars Orbiter Mission and NASA’s MAVEN orbiter arrive just before the comet. MAVEN was designed to study the upper atmosphere of Mars, and carries an ion-neutral mass spectrometer (NGIMS) which could yield information on the interaction of the coma with the Martian upper atmosphere and ionosphere. The NGIMS cover is slated for release just two days before the comet encounter. All spacecraft orbiting Mars may feel the increased drag effects of the encounter.
A simulation of Mars as seen from Comet A1 Siding Spring on closest approach. Created by the author using Starry Night Software.
Proposals for using Earth-based assets for further observations of the comet prior to the event in October are still pending. Amateur observers will be able to follow the approach telescopically, as Comet A1 Siding Spring is expected to reach +8th magnitude in October and pass 7’ from Mars in the constellation Ophiuchus as seen from the Earth. Mars just passed opposition last month, but both will be low to the south west at dusk for northern hemisphere observers in October.
It’s also interesting to consider the potential for interactions of the coma with the surfaces of the moons of Mars as well, though the net amount of water vapor expected to be deposited will not be large.
UPDATE: Check out this nifty interactive simulator which includes Comet A1 Siding Springs courtesy of the Solar System Scope:
The H2O coma of A1 Siding Spring is expected to have a radius of 150,000 kilometres when it passes Mars, just a shade over the nominal flyby distance.
“There is a more extended coma made up of H2O dissociation products (such as hydrogen and hydroxide) that extends for ~1,000,000 kilometres,” researcher at the Department of Planetary Sciences at the University of Arizona and lead author on the paper Roger Yelle told Universe Today.
“Essentially, Mars is in the outer reaches of the coma. The main ion tail misses Mars but there will be some ions from the comet that do reach Mars. The dust tail just misses Mars, which is fortunate.”
The paper also notes that significant perturbations of the upper atmosphere of Mars will occur if the cometary production rate is 10^28 s-1 or larger, which corresponds to about 300 kilograms per second.
“The MAVEN spacecraft will make very interesting observations,” Roger Yelle also told Universe Today. “The comet will perturb primarily the upper atmosphere of Mars and MAVEN was designed to study the upper atmosphere of Mars. Also, it’s just such an incredible coincidence that the comet arrives at Mars less than one month after MAVEN does. MAVEN is nominally in its checkout phase then, and the main science phase of the mission was not scheduled to start until November 1st. However, we are reassessing our plans to see what observations we can make. It’s all quite exciting, and we have to balance safety and the desire to make the best science measurements.”
It’s an unprecedented opportunity, that’s for sure… all eyes will be on the planet Mars and Comet A1 Siding Spring on October the 19th!
A 45-minute time exposure of the southern sky taken in early May shows trailed stars. The fat, bright streak is the planet Mars. Credit: Bob King
A week ago I made a 45-minute time exposure of the southern sky featuring the planet Mars. As the Earth rotated on its axis, the stars trailed across the sky. But take a closer look at the photo and you’ll see something interesting going on.
The trails across the diagonal (upper right to lower left) are straight, those in the top third arc upward or north while those in the bottom third curve downward or south.
I’ve drawn part of the imaginary great circle in the sky called the celestial equator. Residents of cities on or near the Earth’s equator see the celestial equator pass directly overhead. From mid-northern latitudes, it’s about halfway up in the southern sky. From mid-southern latitudes, it’s halfway up in the northern sky. Credit: Bob King
I suspect you know what’s happening here. Mars happens to lie near the celestial equator, an extension of Earth’s equator into the sky. The celestial equator traces a great circle around the celestial sphere much as the equator completely encircles the Earth.
On Earth, cities north of the equator are located in the northern hemisphere, south of the equator in the southern hemisphere. The same is true of the stars. Depending on their location with respect to the celestial equator they belong either to the northern or southern halves of the sky.
Earth’s axis points north to Polaris, the northern hemisphere’s North Star, and south to dim Sigma Octantis. Illustration: Bob King
Next, let’s take a look at Earth’s axis and where each end points. If you live in the northern hemisphere, you know that the axis points north to the North Star or Polaris. As the Earth spins, Polaris appears fixed in the north while all the stars in the northern half of the sky describe a circle around it every 24 hours (one Earth spin). The closer a star is to Polaris, the tighter the circle it describes.
Time exposure centered on Polaris, the North Star. Notice that the closer stars are to Polaris, the smaller the circles they describe. Stars at the edge of the frame make much larger circles. Credit: Bob King
Likewise, from the southern hemisphere, all the southern stars circle about the south pole star, an obscure star named Sigma in the constellation of Octans, a type of navigational instrument. Again, as with Polaris, the closer a star lies to Sigma Octantis, the smaller its circle.
Stars trail around the dim southern pole star Sigma Octantis as seen from the southern hemisphere. The two smudges are the Large and Small Magellanic Clouds, companion galaxies of the Milky Way. Credit: Ted Dobosz
But what about stars on or near the celestial equator? These gems are the maximum distance of 90 degrees from either pole star just as Earth’s equator is 90 degrees from the north and south poles. They “tread the line” between both hemispheres and make circles so wide they appear not as arcs – as the other stars do in the photo – but as straight lines. And that’s why stars appear to be heading in three separate directions in the photograph.
A view of the entire sky as seen from Quito, Ecuador on the equator this evening. The celestial equator crosses directly overhead while each pole star lies 90 degrees away on opposite horizons. Stellarium
In so many ways, we see aspects of our own planet in the stars above.
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 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.
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.
