A low arc, glowing green from excited oxygen, spans the northern sky around 10:30 p.m Central Daylight Time from Duluth, Minn. The Big Dipper is off to the left. Credit: Bob King
Talk of aurora is in the air. Our earlier storytoday by Elizabeth Howell alerted you to the possibility of northern lights. Well, it’s showtime! As of 9:30 p.m. Central Daylight Time, the aurora has been active low in the northern sky.
Subtle pink rays stand above the green arc at 9:35 p.m. CDT. Credit: Bob King
From Duluth, Minn. U.S., a classic green arc low in the northern sky competed with the light of the rising gibbous moon. Once my eyes were dark-adapted, faint parallel rays stood streaked the sky above the arc. NOAA space weather forecasters expect this storm to peak between 1 a.m. CDT and sunrise Friday morning September 12 at a G2or moderate level. Skywatchers across the northern tier of states and southern Canada should see activity across the northern sky. Moonlight will compromise the show, but it rises later each night and dims through the weekend.
The approximate extent of the auroral oval forecast for 11:30 p.m. CDT from Ovation. Credit: NOAA
This is only the start. Things really kick into gear Friday night and Saturday morning when a G3 strong geomagnetic storm is expected from the more direct blast sent our way by the September 10 X1.6 flare. Auroras might be visible as far south as Illinois and Kansas.
We’ll keep you in touch with storm activity by posting regular updates over the next couple days. Including odd hours. Here are some links to check during the night as you wait for the aurora to put in an appearance at your house:
* Ovation oval – shows the approximate extent of the auroral oval that looks like a cap centered on Earth’s geomagnetic pole. During storms, the oval extends south into the northern U.S. and farther.
* Kp index – indicator of magnetic activity high overhead and updated every three hours. A Kp index of “5” means the onset of a minor storm; a Kp of “6”, a moderate storm.
* NOAA space weather forecast
* Advanced Composition Explorer (ACE) satellite plots – The magnetic field direction of the arriving wind from the sun. The topmost graph, plotting Bz, is your friend. When the curve drops into the negative zone that’s good! A prolonged stay at -10 or lower increases the chance of seeing the aurora. Negative numbers indicate a south-pointing magnetic field, which has a greater chance of linking into Earth’s northward-pointing field and wriggling its way past our magnetic defenses and sparking auroras.
The above sequence depicts a rare supernova explosion. The topic panel
Massive stars end their lives dramatically. Once the nuclear fuel deep within their cores is spent, there’s no longer any outward pressure to push against gravity, and the star collapses. But while the inner layers fall in to form a black hole or a neutron star, the outer layers fall faster, hitting the inner layers, and rebounding in a huge supernova explosion.
That’s the textbook definition. But some of these supernovae defy explanation. In 2011 one such explosion, dubbed SN 2011dh, pierced the Whirlpool galaxy, roughly 24 million-light years away. At the time astronomers were baffled. But now, thanks to NASA’s Hubble Space Telescope, they’ve discovered a companion star to this rare supernova and fit the final puzzle pieces together.
SN 2011dh is a Type IIb supernova, unusual in that it contains very little hydrogen and unexplainable via a textbook definition. Even so, astronomers can shed light on the progenitor star simply by digging through archived images from HST. Thanks to HST’s wealth of data and the fact that it observes the Whirlpool galaxy often, two independent research teams both detected a source — a yellow supergiant star — at the right location.
But astronomers don’t think yellow supergiant stars are capable of becoming supernovae … at least not in isolation.
At this point, controversy arose within the astronomical community. Several experts proposed that the observation was a false cosmic alignment and that the actual progenitor was an unseen massive star. Other experts proposed that the progenitor could have been the yellow supergiant, but that it must have belonged in a binary star system.
When a massive star in a binary system overflows its Roche lobe — the region outside that star where gravity dominates — it can pour material onto its smaller companion, therefore losing its hydrogen envelope and shrinking in mass.
At the time the mass-donor explodes, the companion star should be a massive blue star, having gained material during the mass transfer. Its high temperature should also cause it to emit mostly in the ultraviolet range, therefore rendering it invisible in any visible images.
So Gastón Folatelli from the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) and colleagues decided to take a second look at the mysterious supernova in ultraviolet light. And their observations matched their expectations. The original supernova had faded, and a different point source had taken its place.
“One of the most exciting moments in my career as an astronomer was when I displayed the newly arrived HST images and saw the object right there, where we had anticipated it to be all along,” said Folatelli in a news release.
The research illustrates the intricate interplay between theory and observation. Astronomers often rely on theories long before they gain the technology necessary to provide the correct observations or spend years trying to explain odd observations with complex theoretical modeling. More often, however, the two coexist as theory and observation banter back and forth.
The findings have been published in the Astrophysical Journal Letters and are available online.
An image of globular cluster M54 taken by the Very Large Telescope Survey Telescope at the European Southern Observatory's Paranal Observatory in northern Chile. Credit: ESO
This new picture of M54 — a part of a satellite galaxy to the Milky Way called the Sagittarius Dwarf Galaxy — is part of a “test case” astronomers have to figure out a mystery of missing lithium.
For decades, astronomers have been aware of a dearth of lithium in our own galaxy, the Milky Way. This image from the Very Large Telescope’s Survey Telescope represents the first effort to probe for the element outside of our galaxy.
“Most of the light chemical element lithium now present in the Universe was produced during the Big Bang, along with hydrogen and helium, but in much smaller quantities,” the European Southern Observatory stated.
“Astronomers can calculate quite accurately how much lithium they expect to find in the early Universe, and from this work out how much they should see in old stars. But the numbers don’t match — there is about three times less lithium in stars than expected. This mystery remains, despite several decades of work.”
In any case, observations of M54 show that the amount of lithium there is similar to the Milky Way — meaning that the lithium problem is not confined to our own galaxy. A paper based on the research was published in the Monthly Notices of the Royal Astronomical Society. The research was led by Alessio Mucciarelli at the University of Bologna in Italy.
A map of Saturn's F ring from 2006 shows one of the few bright, extended clumps (indicated by a green box) seen during six years of observation by Cassini. Image credit: NASA/JPL-Caltech/SSI
Nothing stands still. Everything evolves. So why shouldn’t Saturn’s kookie, clumpy F ring put on a new face from time to time?
A recent NASA-funded study compared the F ring’s appearance in six years of observations by the Cassini mission to its appearance during the Saturn flybys of NASA’s Voyager mission, 30 years earlier.
A kink in part of Saturn’s F ring. While the ring is held together by the shepherd moons Prometheus and Pandora, which orbit just inside and outside the ring, embedded moonlets are believed responsible for the kinks and clumps. The rings is several hundred kilometers wide. Credit: NASA
While the F ring has always displayed clumps of icy matter, the study team found that the number of bright clumps has nose-dived since the Voyager space probes saw them routinely during their brief flybys 30 years ago. Cassini spied only two of the features during a six-year period.
Scientists have long suspected that moonlets up to 3 miles (5 km) wide hiding in the F ring are responsible for its uneven texture. Kinks and knots appear and disappear within months compared to the years of observation needed changes in many of the other rings.
Saturn’s F ring is extremely narrow compared to the historic A, B and C rings. It measures just a few hundred kilometers across. Credit: NASA/Cassini
“Saturn’s F ring looks fundamentally different from the time of Voyager to the Cassini era,” said Robert French of the SETI Institute in Mountain View, California, who led the study along with SETI Principal Investigator Mark Showalter. “It makes for an irresistible mystery for us to investigate.”
A 2007 artist impression of small boulder-like chunks of ice that comprise Saturn’s rings. The largest are about 10-12 feet across.They clump together to form elongated, curved aggregates, continually forming and dispersing. Credit: NASA/JPL/Univ. of Colorado
Because the moonlets lie close to the ring and cross through it every orbit, the research team hypothesizes that the clumps are created when they crash into and pulverize smaller ring particles during each pass. They suspect that the decline in the number of exceptionally bright kinks and the clumps echoes a decline in the number of moonlets available to do the job.
So what happened between Voyager and Cassini? Blame it on Prometheus. The F ring circles Saturn at a delicate point called the Roche Limit. Any moons orbiting closer than the limit would be torn apart by Saturn’s gravitational force.
The culprit? Prometheus measures 74 miles (119 km) across and orbits the inner edge of Saturn’s F ring. Credit: NASA
“Material at this distance from Saturn can’t decide whether it wants to remain as a ring or coalesce to form a moon,” said French. “Prometheus orbits just inside the F ring, and adds to the pandemonium by stirring up the ring particles, sometimes leading to the creation of moonlets, and sometimes leading to their destruction.”
Every 17 years the orbit of Prometheus aligns with the orbit of the F ring in a way that enhances its gravitational influence. The researchers think the alignment spurs the creation of lots of extra moonlets which then go crashing into the ring, creating bright clumps of material as they smash themselves to bits against other ring material.
Sounds like a terrifying version of carnival bumper cars. In this scenario, the number of moonlets would gradually drop off until another favorable Prometheus alignment.
The Voyagers encounters with Saturn occurred a few years after the 1975 alignment between Prometheus and the F ring, and Cassini was present for the 2009 alignment. Assuming Prometheus has been “working” to build new moons since 2009, we should see the F ring light up once again with bright clumps in the next couple years.
As the Chinese proverb says, “May you live in interesting times,” and while the promise of Comet ISON dazzling observers didn’t exactly pan out as hoped for in early 2014, we now have a bevy of binocular comets set to grace evening skies for northern hemisphere observers. Comet 2012 K1 PanSTARRS has put on a fine show, and comet C/2014 E2 Jacques has emerged from behind the Sun and its close 0.085 AU passage near Venus and has already proven to be a fine target for astro-imagers. And we’ve got another icy visitor to the inner solar system beating tracks northward in the form of Comet C/2013 V5 Oukaimeden, and a grand cometary finale as comet A1 Siding Spring brushes past the planet Mars. That is, IF a spectacular naked eye comet doesn’t come by and steal the show, as happens every decade or so…
Comet E2 Jacques crossing Cassiopeia as seen from the island of Malta. Credit: Leonard Mercer.
Anyhow, here’s a rapid fire run down on what you can expect from three of these binocular comets that continue to grace the twilight skies this Fall.
(Note that mentions of comets “passing near” a given object denote conjunctions of less than an angular degree of arc unless otherwise stated).
C/2014 E2 Jacques:
Discovered by amateur astronomer Cristovao Jacques on March 13th of this year from the SONEAR Observatory in Brazil, Comet E2 Jacques has been dazzling observers as it passed 35 degrees from the north celestial pole and posed near several deep sky wonders as it transited the constellation of Cassiopeia.
Comet E2 Jacques on August 28th as seen from the MVAS dark sky site in Yellow Springs, Ohio. Credit: John Chumack.
Mid-September finds Jacques 55 degrees above the NE horizon at dusk for northern hemisphere viewers in the constellation Cygnus. It then races southward parallel to the galactic equator, keeping in the +7th to +8th magnitude range before dropping down below +10th magnitude in late October. After this current passage through the inner solar system, Comet Jacques will be on a shortened 12,000 year orbit.
-Brightest: Mid-August at +6th magnitude.
-Perihelion: July 2nd, 2014 (0.66 AU).
-Closest to Earth: August 28, 2014 (0.56 AU).
Some key upcoming dates:
Sep 10: Passes the +3.9 magnitude star Eta Cygni.
Sep 14: Passes near the famous optical double star Albireo and crosses into the constellation of Vulpecula.
Sep 16: Passes in front of the +4.4 magnitude star Alpha Vulpeculae.
Sep 20: Crosses the Coathanger asterism.
Sep 21: Crosses into the constellation Sagitta.
Sep 24: Crosses into Aquila.
The celestial path of Comet Jacques from September 12th through November 1st. (All simulations created using Starry Night Education software.
Oct 5: Crosses the galactic plane.
Oct 14: passes near the +7.5 magnitude open cluster NGC 6755.
Oct 15: Drops back below +10th magnitude?
C/2013 V5 Oukaïmeden
Pronounced Ow-KAY-E-Me-dah, (yes, it’s a French name, with a very metal umlaut over the “ï”!) comet C/2013 V5 Oukaïmeden was discovered by the Moroccan Oukaïmeden Sky Survey (MOSS) located in the Atlas Mountains in Morocco. After completing a brief dawn appearance in early September, the comet moves into the dusk sky and starts the month of October located 38 degrees east of the Sun at about 14 degrees above the southwestern horizon as seen from latitude 30 degrees north at sunset. Southern hemisphere observers will continue to have splendid dawn views of the comet through mid-September at its expected peak. Comet Oukaïmeden is currently at +8th magnitude “with a bullet” and is expected to top out +6th magnitude in late September shortly before perihelion and perhaps remain a binocular object as it crosses the constellation Libra in October.
An early image of Comet C/2013 V5 Oukaimeden taken in February of this year. Credit: Efrain Morales Rivera.
And its also worth noting that as comet A1 Siding Spring (see below) makes a close physical pass by Mars on October 19th, Comet Oukaïmeden makes a close apparent pass by Saturn as seen from our Earthly vantage point the evening before! To be sure, the dusk apparition of Comet Oukaïmeden will be a tough one, but if you can track down these bright guidepost objects listed below, you’ll have a chance at spying it.
-Brightest: Mid-September.
-Perihelion: September 28th, 2014 (0.63 AU from the Sun).
-Closest to Earth: September 16th, 2014 (0.48 AU).
Some key upcoming dates:
Sep 10 through Oct 4: Threads across the borders of the constellations Hydra, Pyxis, Antlia and Centaurus.
Sep 18: Passes near the +3.5 magnitude star Xi Hydrae.
Sep 19: Passes near the +4.3 magnitude star Beta Hydrae.
Sep 25: Passes 1.5 degrees from the +8th magnitude Southern Pinwheel Galaxy M83.
Oct 1: Passes in front of the +10.2 globular cluster NGC 5694.
The path of Comet Oukaimeden through the month of October: The Sun position is shown for the final date.
Oct 3: Passes into Libra.
Oct 11: Passes near the +8.5 magnitude globular cluster NGC 5897.
Oct 16: Crosses the ecliptic plane northward.
Oct 18: Passes less than two degrees from Saturn.
Oct 25: Passes less than a degree from the 2 day old Moon and the +3.9 magnitude star Gamma Librae.
The projected light curve for Comet Oukaimeden with observational measurements (black dots). Credit: Seiichi Yoshida.
C/2013 A1 Siding Spring
This comet was discovered on January 3rd, 2013 from the Siding Spring observatory in Australia, and soon caught the eye of astronomers when it was discovered that it would make a nominal pass just 139,000 kilometres from Mars on October 19th.
Comet A1 Siding Spring as seen from NEOWISE early this year. Credit: NASA/JPL.
As seen from the Earth, Comet A1 Siding Spring has just broken 10th magnitude and vaults up towards the planet Mars low to the southwest at dusk this Fall for northern hemisphere observers. A1 Siding Spring is expected to top out at +8th magnitude this month before its Mars encounter, and is on a one million year plus orbit.
-Brightest: Early to Mid-September.
-Perihelion: October 25th, 2014.
-Closest to Earth: October 28th, 2014 (1.4 AU).
Some key upcoming dates:
Sep 17: Passes into the constellation Telescopium.
Sep 20: Passes near the +8.5 magnitude globular NGC 6524.
Sep 21: Passes into the constellation Ara.
Sep 22: Passes the +3.6 magnitude star Beta Arae.
Sep 25: Crosses into Scorpius.
Sep 30: Passes the +3 magnitude star Iota Scorpii.
Mars and Comet A1 Siding Springs crossing paths through the month of October.
Oct 3: Passes near the +7.2 magnitude globular NGC 6441.
Oct 5: Passes 2 degrees from Ptolemy’s cluster M7.
Oct 8: Passes in front of the Butterfly cluster M6.
Oct 10: Crosses the galactic plane.
Oct 11: Crosses into Ophiuchus.
Oct 19: Passes just 2’ arc minutes from Mars as seen from Earth.
Oct 22: Passes north of the ecliptic.
Oct 30: Drops back below +10th magnitude?
Key moonless windows for evening comet viewing as reckoned from when the Moon wanes from Full to New are: September 9th to September 24th and October 8th to the 23rd.
Looking for resources to find out just what these comets and others are up to? The COBS Comet Observers database is a great resource for recent observations, as is Seiichi Yoshida’s Weekly Comet page. For history and current info, Gary Kronk’s Cometography is also a great treasure trove to delve into, as are the Yahoo! Comet and Comet Observer mailing lists.
Be sure to check out these fine icy visitors to the inner solar system coming to a sky near you. We fully expect to see more outstanding images of these comets and more filling up the Universe Today Flickr forum!
On either side of the white line in the picture are two models of how dark matter is distributed in a galaxy similar to the Milky Way. At left, non-interacting cold dark matter creates satellite galaxies. At right, dark matter interacting with other particles makes the number of observed satellite galaxies smaller. Credit: Durham University
Funny how small particle interactions can have such a big effect on the neighbors of the Milky Way. For a while, scientists have been puzzled about the dearth of small satellite galaxies surrounding our home galaxy.
They thought that cold dark matter in our galaxy should encourage small galaxies to form, which created a puzzle. Now, a new set of research suggests the dark matter actually interacted with small bits of normal matter (photons and neutrinos) and the dark matter scattered away, reducing the amount of material available for building galaxies.
“We don’t know how strong these interactions should be, so this is where our simulations come in,” stated Celine Boehm, a particle physicist at Durham University who led the research. “By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.”
Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. Hurt
Dark matter is a poorly understood part of the Universe, which is frustrating for scientists because it (along with dark energy) is believed to make up the majority of our Cosmos. There are several postulated types of it, but the main thing to understand is dark matter is hard to detect (except, in certain cases, through its interactions with gravity.)
This isn’t the only explanation for why the galaxies are missing, the scientists caution. Perhaps the universe’s first stars were so hot that they affected the gas that other stars formed from, for example.
An artist’s rendering of the newly discovered exoplanet OGLE-2013-BLG-0341LBb (far right) orbiting one star (right) of a binary red dwarf star system, from an Earth-type distance of approximately 0.9 Astronomical Units away. Image Credit: Cheongho Han, Chungbuk National University, Republic of Korea
Our solar neighborhood is rich with planetary systems. Within 20 light-years we’ve detected sizzling gas giants and rocky planets orbiting closer to their host star than Mercury orbits the Sun.
Astronomers have now added one more to the list, and this one — a super-Earth dubbed Gliese 15Ab — ranks as one of the closest known exoplanets, circling its host star only 11.7 light-years away.
Gliese 15 is a binary system, with two cool, dim red dwarfs orbiting each other. Although red dwarfs are the most common type of star in the galaxy, they’re so intrinsically faint that not a single one (including the closest star to the Sun, Proxima Centauri) is visible to the naked eye.
Although Gliese 15A might appear faint from Earth, it is overwhelmingly bright compared to its barely reflective exoplanet. So unfortunately we can’t easily see the exoplanet directly. But it does leave an imprint on its host star. Its small gravitational tug makes Gliese 15A wobble ever so slightly as both orbit a mutual center of mass, known as the barycenter.
The star’s movement is then imprinted on its spectrum. As Gliese 15A moves away from the Earth, its spectral lines stretch to redder wavelengths. But as it moves toward the Earth, its spectral lines compress to shorter wavelengths.
The radial velocities for Gliese 15Ab. Image Credit: Howard et al.
The change is minute. But the Keck 10-meter telescope, with an extremely high-resolution detector, can see such small changes. And from this tiny wobble, Andrew Howard and colleagues calculated that the planet is 5.35 times the mass of Earth and orbits its star in only 11.44 days, making it a hot super-Earth. And remember, it’s only 11.7 light-years away.
A handful of other planet candidates have been found that are closer, but all — including Gliese 15Ab — have yet to be confirmed by other research teams. In the long run, it may turn out that this hot super-Earth is the closest planet to our pale blue dot. Then again, it may not. That’s how science works.
Nonetheless, Gliese 15Ab might prove to be an exciting target for one of the new planet imagers that came online within the past year.
The findings will be published in the Astrophysical Journal and are available online.
The suspect crater on the outskirts of Managua. Credit: AP/BBC News
By now, you’ve seen the pictures.
As astronomers tracked the close pass of Near Earth Asteroid 2014 RC this weekend, reports came out of Nicaragua that a possible meteorite struck near the capital of Managua.
Details are still sketchy, but government sources cite reports of a loud bang and ground tremor late Saturday night on September 6th. Later images circulating late Sunday evening showed a crater 12 metres wide and 5.5 metres deep on a remote section of the international airport at Managua, which also hosts a local air force installation.
A closer look at the Managua crater. Credit: AFP/BBC News.
Reports state that the impact went off “like a bomb,” and Wilfried Strauch of the Nicaragua Institute of Earth Studies has already gone on record as being “convinced it was a meteorite.” Investigators are currently scouring the alleged impact site for debris.
This has also sparked a lively discussion across forums and social media: is the crater the result of an extraterrestrial impactor?
Of course, cosmic coincidences can and do happen. Last year, the close passage of asteroid 2012 DA14 was upstaged by the explosion of a 20-metre asteroid over the city of Chelyabinsk on the very same day. And though the two were conclusively proven to be unrelated, they did serve to raise general human awareness that, yes, large threatening rocks do indeed menace the Earth. And ironically, the aforementioned asteroid 2014 RC was about the same size as the Chelyabinsk asteroid, which snuck up on the Earth undetected from a sunward direction.
But Ron Baalke, a software engineer at the Jet Propulsion Laboratory has posted an update to the close pass by asteroid 2014 RC on the NASA’s Near Earth Object website, saying, “Since the explosion in Nicaragua occurred a full 13 hours before the close passage of asteroid 2014 RC, these two events are unrelated.”
Baalke also noted that “no eyewitness accounts or imagery have come to light of the fireball flash or debris trail that is typically associated with a meteor of the size required to produce such a crater.”
The epic airburst over Chelyabinsk as captured via dashcam. (Still from video).
There are a few other problems with the Managua crater, though of course, we’d love to be proven wrong. Many observers have noted that the crater does not appear to look fresh, and the trees and soil around it appear to be relatively undisturbed. A first visual impression of the site looks more like a ground slump or sinkhole than an impact, or perhaps an excavation. Others have also noted the similarity of the crater with a military blast, a very good possibility with an air force base nearby.
Meteorite Men’s own Geoff Notkin has voiced doubts as to the authenticity of the meteor crater on Twitter.
Of course, it’s possible (though unlikely) that the impactor struck the site from straight overhead, leaving the area around it undisturbed. As with meteor showers, an impactor striking the Earth before local midnight would be coming at the planet from behind at a lower combined velocity.
Color me skeptical on this one. Still, we’ve been wrong before, and it’s always a boon for science when a new meteorite fall turns out to be real. Many have already cited the similarities between the Managua crater and the Carancas event in 2007 in Peru near Lake Titicaca that was initially considered dubious as well.
But again, it’s highly improbable that the Managua event is related to 2014 RC, however, which made its closest pass over the southern hemisphere near New Zealand many hours later at 18:18 UT on Sept 7th. We ran a recent simulation of the pass in Starry Night from the vantage point of the asteroid, and you’ll note that Central America is well out of view:
It’s also curious that no still images or video of the Managua event have yet to surface. This is strange, as it occurred on a Saturday night near a capital city of 2.4 million. The weather over Managua was partly cloudy that night, and generally, a security camera or two usually catches sight of the fireball.
We also did a check through any upcoming space junk reentries, which also proved to be a poor fit for a potential suspect. The next slated reentry is a BREEZE-M Tank with the NORAD ID of 2011-074D associated with the 2011 launch of AMOS-5. This object was not overhead around the time of the Managua event, and is predicted to reenter on September 9th at 15:15 UT +/- 14 hours.
And the same goes for the launch of AsiaSat-6 by SpaceX on Saturday night, as launches from the Cape head out eastward across the Atlantic and away from the Gulf of Mexico region.
A look at 2014 RC on the night of September 6th. Credit: Gianluca Masi and the Virtual Telescope Project.
Unfortunately, images and video would go a long way towards gauging a direction and final orbit of a suspect meteorite. The discovery of meteoritic debris at the site would also serve to clinch the link between the crater and a cosmic impactor as well. Or perhaps, news of the impending passage of NEO asteroid 2014 RC and the recent pass of 2014 RA the weekend prior had already primed the general public to suspect a meteor strike as an explosion was heard late in the evening… we’ve lived near bombing ranges, and are familiar with the sound of late night explosions ourselves.
Target Earth… An aerial view of Pingualuit crater in northern Quebec. Credit: NASA/Denis Sarrazin and the Pingualuit Crater Lakes project.
To be sure, the universe is a dangerous place, and errant rocks from above do on occasion have it out for any unwary species that gets in their way.
So we’ll open it up for discussion: what do you think happened on Saturday night near Managua? Was it a meteorite, or another case of a “meteor-wrong?”
A composite image of Rosetta's target (Comet 67P/Churyumov–Gerasimenko) obtained by the Very Large Telescope. Credit: C. Snodgrass/ESO/ESA
This picture shows it is possible to look at Rosetta’s comet from Earth, but what a lot of work it requires! The picture you see above is a composite of 40 separate images taken by the Very Large Telescope (removing the background stars).
Despite the fact that Rosetta is right next to Comet 67P/Churyumov–Gerasimenko, ground-based observatories are still useful because they provide the “big picture” on what the comet looks like and how it is behaving. It’s an observational challenge, however, as the comet is still more than 500 million kilometers (310 million miles) from the Sun and hard to see.
On top of that, the European Space Agency says the comet is sitting in a spot in the sky where it is difficult to see it generally, as the Milky Way’s prominent starry band is just behind. But what can be seen is spectacular.
“Although faint, the comet is clearly active, revealing a dusty coma extending at least 19 000 km [11,800 miles] from the nucleus,” ESA stated. “The comet’s dusty veil is not symmetrical as the dust is swept away from the Sun – located beyond the lower-right corner of the image – to begin forming a tail.”
And that dust is beginning to show up in Rosetta’s grain collector, as you can see below!
Rosetta’s dust collector, Cometary Secondary Ion Mass Analyser (COSIMA), collected its first grains from Comet 67P/Churyumov–Gerasimenko in August 2014. This image shows before and after images of the collection. Credit: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/ BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S
Rosetta’s Cometary Secondary Ion Mass Analyser (COSIMA) picked up several dust grains in August, which you can see in the image, and are now looking at the target plate more closely to figure out more about the dust grains.
“Some will be selected for further analysis: the target plate will be moved to place each chosen grain under an ion gun which will then ablate the grain layer by layer. The material is then analyzed in a secondary ion mass spectrometer to determine its composition,” ESA stated.
All of these results were presented today (Sept. 8) at the European Planetary Science Congress 2014.
MAVEN is NASA’s next Mars Orbiter and will investigate how the planet lost most of its atmosphere and water over time. Credit: NASA
MAVEN to conduct up close observations of Comet Siding Spring during Oct. 2014 MAVEN is NASA’s next Mars Orbiter and will investigate how the planet lost most of its atmosphere and water over time. Credit: NASA
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NASA’s MAVEN Mars Orbiter is “ideally” instrumented to uniquely “map the composition of Comet Siding Spring” in great detail when it streaks past the Red Planet during an extremely close flyby on Oct. 19, 2014 – thereby providing a totally “unexpected science opportunity … and a before and after look at Mars atmosphere,” Prof. Bruce Jakosky, MAVEN’s Principal Investigator of CU-Boulder, CO, told Universe Today in an exclusive interview.
The probes state-of-the-art ultraviolet spectrograph will be the key instrument making the one-of-a-kind compositional observations of this Oort cloud comet making its first passage through the inner solar system on its millions year orbital journey.
“MAVEN’s Imaging Ultraviolet Spectrograph (IUVS) is the ideal way to observe the comet coma and tail,” Jakosky explained.
“The IUVS can do spectroscopy that will allow derivation of compositional information.”
“It will do imaging of the entire coma and tail, allowing mapping of composition.”
Comet: Siding Spring The images above show — before and after filtering — comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on NASA’s Hubble Space Telescope. Image Credit: NASA, ESA, and J.-Y. Li (Planetary Science Institute)
Moreover the UV spectrometer is the only one of its kind amongst NASA’s trio of Martian orbiters making its investigations completely unique.
“IUVS is the only ultraviolet spectrometer that will be observing the comet close up, and that gives the detailed compositional information,” Jakosky elaborated
And MAVEN, or the Mars Atmosphere and Volatile Evolution, is arriving just in the nick of time to fortuitously capture this fantastically rich data set of a pristine remnant from the solar system’s formation.
The spacecraft reaches Mars in less than 15 days. It will rendezvous with the Red Planet on Sept. 21 after a 10 month interplanetary journey from Earth.
Furthermore, since MAVEN’s purpose is the first ever detailed study of Mars upper atmosphere, it will get a before and after look at atmospheric changes.
“We’ll take advantage of this unexpected science opportunity to make observations both of the comet and of the Mars upper atmosphere before and after the comet passage – to look for any changes,” Jakosky stated.
How do MAVEN’s observations compare to NASA’s other orbiters Mars Odyssey (MO) and Mars Reconnaissance Orbiter (MRO), I asked?
“The data from the other orbiters will be complementary to the data from IUVS.”
“Visible light imaging from the other orbiters provides data on the structure of dust in the coma and tail. And infrared imaging provides information on the dust size distribution.”
IUVS is one of MAVENS’s nine science sensors in three instrument suites targeted to study why and exactly when did Mars undergo the radical climatic transformation.
How long will MAVEN make observations of Comet C/2013 A1 Siding Spring?
“We’ll be using IUVS to look at the comet itself, about 2 days before comet nucleus closest approach.”
“In addition, for about two days before and two days after nucleus closest approach, we’ll be using one of our “canned” sequences to observe the upper atmosphere and solar-wind interactions.”
“This will give us a detailed look at the upper atmosphere both before and after the comet, allowing us to look for differences.”
Describe the risk that Comet Siding Spring poses to MAVEN, and the timing?
“We have the encounter with Comet Siding Spring about 2/3 of the way through the commissioning phase we call transition.”
“We think that the risk to the spacecraft from comet dust is minimal, but we’ll be taking steps to reduce the risk even further so that we can move on toward our science mission.”
“Throughout this entire period, though, spacecraft and instrument health and safety come first.”
This graphic depicts the orbit of comet C/2013 A1 Siding Spring as it swings around the sun in 2014. On Oct. 19, 2014 the comet will have a very close pass at Mars. Its nucleus will miss Mars by about 82,000 miles (132,000 kilometers). Credit: NASA/JPL-Caltech
What’s your overall hope and expectation from the comet encounter?
“Together [with the other orbiters], I’m hoping it will all provide quite a data set!
“From Mars, the comet truly will fill the sky!” Jakosky gushed.
The comet’s nucleus will fly by Mars at a distance of only about 82,000 miles (132,000 kilometers) at 2:28 p.m. ET (18:28 GMT) on Oct. 19, 2014. That’s barely 1/3 the distance from the Earth to the Moon.
What’s the spacecraft status today?
“Everything is on track.”
Maven spacecraft trajectory to Mars on Sept. 4, 2014. Credit: NASA
The $671 Million MAVEN spacecraft’s goal is to study Mars upper atmosphere to explore how the Red Planet lost most of its atmosphere and water over billions of years and the transition from its ancient, water-covered past, to the cold, dry, dusty world that it has become today.
MAVEN soared to space over nine months ago on Nov. 18, 2013 following a flawless blastoff from Cape Canaveral Air Force Station’s Space Launch Complex 41 atop a powerful Atlas V rocket and thus began a 10 month interplanetary voyage from Earth to the Red Planet.
It is streaking to Mars along with ISRO’sMOM orbiter, which arrives a few days later on September 24, 2014.
So far it has traveled 95% of the distance to the Red Planet, amounting to over 678,070,879 km (421,332,902 mi).
As of Sept. 4, MAVEN was 205,304,736 km (127,570,449 miles) from Earth and 4,705,429 km (2,923,818 mi) from Mars. Its Earth-centered velocity is 27.95 km/s (17.37 mi/s or 62,532 mph) and Sun-centered velocity is 22.29 km/s (13.58 mi/s or 48,892 mph) as it moves on its heliocentric arc around the Sun.
One-way light time from MAVEN to Earth is 11 minutes and 24 seconds.
MAVEN is NASA’s next Mars orbiter and launched on Nov. 18, 2014 from Cape Canaveral, Florida. It will study the evolution of the Red Planet’s atmosphere and climate. Universe Today visited MAVEN inside the clean room at the Kennedy Space Center. With solar panels unfurled, this is exactly how MAVEN looks when flying through space and circling Mars and observing Comet Siding Spring. Credit: Ken Kremer/kenkremer.com
Stay tuned here for Ken’s continuing MAVEN, MOM, Rosetta, Opportunity, Curiosity, Mars rover and more Earth and planetary science and human spaceflight news.
NASA’s Mars bound MAVEN spacecraft launches atop Atlas V booster at 1:28 p.m. EST from Space Launch Complex 41 at Cape Canaveral Air Force Station on Nov. 18, 2013. Image taken from the roof of the Vehicle Assembly Building (VAB) at NASA’s Kennedy Space Center. Credit: Ken Kremer/kenkremer.comNASA’s MAVEN Mars orbiter, chief scientist Prof. Bruce Jakosky of CU-Boulder and Ken Kremer of Universe Today inside the clean room at the Kennedy Space Center on Sept. 27, 2013. MAVEN launched to Mars on Nov. 18, 2013 from Florida. Credit: Ken Kremer/kenkremer.com
