Photos of the white spots within the 57-mile-wide on Ceres photographed on May 3 and 4 by NASA's Dawn spacecraft. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA / montage by Tom Ruen
We don’t know exactly what those mysterious white spots on Ceres are yet, but we’re getting closer to an explanation. Literally. The latest images from the Dawn spacecrafttaken a mere 8,400 miles from the dwarf planet Ceres reveal that the pair of spots are comprised of even more spots.
“Dawn scientists can now conclude that the intense brightness of these spots is due to the reflection of sunlight by highly reflective material on the surface, possibly ice,” said Christopher Russell, principal investigator for the Dawn mission from the University of California, Los Angeles.
This animation shows a sequence of images taken by NASA’s Dawn spacecraft on May 4, 2015, from a distance of 8,400 miles (13,600 km), in its RC3 or science mapping orbit. The image resolution is 0.8 mile (1.3 km) per pixel. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Dawn recently concluded its first science orbit, making a 15-day full circle around Ceres while gathering data with its suite of science instruments. This past Saturday, May 9, its ion engine fired once again to lower the spacecraft to its second science orbit which it will enter on June 6. On that date, the probe will hover just 2,700 miles (4,400 km) above the dwarf planet and begin a comprehensive mapping of the surface. Scientists also hope the bird’s eye view will reveal clues of ongoing geological activity.
Check out this great video compiled from Dawn’s still frames of Ceres by Tom Ruen. Almost feels like you’re there.
There’s no doubt a lot’s been happening on Ceres. One look at all those cracks hint at either impact-related stresses some kind of crustal expansion. Geological processes may still make this little world rock and roll.
In this uncropped single frame, not only are multiple white spots visible but also long, roughly parallel cracks or troughs in Ceres’ surface. Are they impact-related or caused by some other stress? Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA
Fortunately, we won’t have to wait till next month for more photos. NASA plans to pause the probe twice on the way down to shoot and send fresh images.
Comet C/2014 Q2 Lovejoy on May 7 with its emerald coma and faint gas tail. Lovejoy is currently around magnitude +7.5 and slowly fading. Credit: Rolando Ligustri
Lots of towns hold a polar plunge fundraising event in the winter. Duluth, Minnesota’s version, where participants jump in Lake Superior every February, might just be the coldest. Comet Lovejoy’s a season behind, but sure enough, it’s following suit, diving deep into the dark waters of the north celestial pole this month.
I dropped in on our old friend last night, when it glowed only 8° from the North Star. In 8×40 binoculars, the comet was faintly visible as a hazy blob of light with a brighter center. Not a sight to knock you over, but the fact that this comet is still visible in binoculars after so many months makes it worthwhile to seek out. Moonless skies for the next 10-11 nights means lots of opportunities.
Just face the North Star (Polaris) to begin tracking Comet Lovejoy. The map shows the sky facing north around 10:30 p.m. local time in mid-May. Stars are plotted to magnitude +8. Click for a larger version. Source: Chris Marriott’s SkyMap
Unless a new comet is discovered, Lovejoy will continue to remain the only “bright” comet visible from mid-northern latitudes for some time. There’s a tiny chance Comet C/2014 Q1 PanSTARRS will wax bright enough to see in twilight in early July, but it will be very low in the northwestern sky at dusk and visible for a few nights at most. Only C/2013 US10 Catalina offers the chance for a naked eye / binocular appearance, when it re-emerges from the solar glare in the latter half of November in the morning sky.
Southern hemisphere observers have more to smile about with Comet C/2015 G2 MASTERcurrently flaunting its fluff at magnitude +6.6 or just under the naked eye limit. They’ll also get a far better view of C/2014 Q1 PanSTARRS come this July and August.
Wide view of the sky facing north in mid-May around 10:30 p.m. local time. Use the Pointer stars in the Big Dipper to point you to Polaris and from there to the comet. Source: Chris Marriott’s SkyMap
Through a telescope, Lovejoy still shows off a round, 6 arc minute diameter coma (one-fifth as wide as a full moon) and a denser, brighter core highlighted by a starlike false nucleus. We call it false because the true comet nucleus, probably no more than a few kilometers across, hides within a dusty cocoon of its own making. Only spacecraft have been able to get close enough for a clear view of comet nuclei. Each shows a unique and usually non-spherical shape because comets aren’t massive enough for their own self-gravity to crush them into spheres the way larger moons and planets do. If you’re a single object and big, being spherical comes naturally.
Comet Lovejoy will be closest to the imaginary point in the sky called the north celestial pole on May 29. Polaris lies 0.75° from the pole and describes a small circle 1.5° in diameter around it each day. Source: Stellarium
In my 15-inch (37-cm) telescope a faint wisp of a tail poked from the coma to the north. Looking at the map, you can see the comet’s headed due north through Cepheus toward Polaris, the North Star. Each passing night, it draws closer to the sky’s celestial pivot point, missing it by just 1° on the evenings of May 27 and 28. Closest approach to the north celestial pole, which marks the spot in the sky toward which Earth’s north polar axis currently points, occurs on May 29 with a separation of 54 arc minutes or just under a degree.
Finding Polaris is easy. Just draw a line through the two stars at the end of of the Big Dipper’s Bowl toward the horizon. The first similarly bright star you run into is the North Star. Using the map, you can navigate from Polaris to the fuzzy comet with either binoculars or telescope.
Newly found asteroid 2015 HD1 will pay a close visit to Earth overnight, zipping by at just 45,600 miles at 3:11 a.m. Tuesday morning. Credit: Gianluca Masi
If you wake up in the middle of the night with weird dreams about flying asteroids, I wouldn’t be surprised. Around 3 a.m. (CDT) tomorrow morning April 21, a 50-foot-wide asteroid will hurdle just 0.2 lunar distances or 45,600 miles over your bed.
The Mt. Lemmon Survey, based in Tucson, Arizona, snagged the space rock Saturday. 2015 HD1 is about as big as a full grown T-rex through not nearly as scary, since it will safely miss Earth … but not by much.
Artist view of a small asteroid passing near Earth. Credit: NASA
Geostationary satellites, used for global communications, weather forecasting and satellite TV, are parked in orbits about 22,300 miles above the Earth. 2015 HD1 will zip by at just twice that distance, putting it in a more select group of extremely close-approaching objects. Yet given its small size, even if it were to collide with Earth, this dino-sized rock would probably break up into a shower of meteorites.
Lucky for all of us, astronomers conducting photographic surveys like the one at Mt. Lemmon rake the skies every clear night, turning up a dozen or more generally small, Earth-approaching asteroids every month. None yet has been found on a collision course with Earth, but many pass within a few lunar distances.
A common misunderstanding about approaching asteroids concerns Earth’s gravity. While our planet has plenty of gravitational pull, it’s no match for speedy asteroids. We can’t “pull” them in like some tractor beam.
Because they’re moving at miles per second velocities, they have lots of angular momentum (desire to keep moving in the direction they’re headed). Only asteroids headed directly for us have any hope of striking our atmosphere and potentially leaving fragments behind as meteorites.
Still, both Earth and asteroid interact. Close-approaching asteroids often will have their orbits altered by Earth’s gravity. They come in in one direction and leave on a slightly different one after Earth weighs in (literally!)
All the known asteroids orbiting the Sun – in 3D
Moving rapidly across the constellations Hydra, Antlia and Puppis tomorrow morning, 2015 HD1 is expected to reach climb briefly to magnitude +13.2. That’s faint, but with a good map, amateur astronomers with 8-inch or larger telescopes will see it move in real time across the sky like a slow satellite. To create a map, you’ll need sky-charting software like MegaStar, The Sky or Starry Night and these orbital elements.
Maximum brightness and visibility occurs between about 1 and 3 a.m CDT (6-8 UT) for observers in low northern or southern latitudes. From the West Coast, the asteroid will be low in the southwestern sky around 10 p.m. local time. Hawaiian skywatchers will get the brightest views with the asteroid highest in the sky around 9 p.m. local time. IF you live in the eastern two-thirds of the U.S., it’s either too far south or will have set by the time it’s bright enough to see.
No worries. Italian astronomer Gianluca Masi will once again fire up his telescope to provide live views of 2015 HD1 on his Virtual Telescope Project websitetoday April 20 starting at 4 p.m. CDT (21:00 UT). So if you like, you can get a gander after all.
A day-old Moon floats over the Spirit Mountain ski hill in Duluth, Minn. this past January. Credit: Bob King
16th century Spanish explorer Juan Ponce de León looked and looked but never did find the Fountain of Youth, a spring rumored to restore one’s youth if you bathed or drank from its waters. If he had, I might have interviewed him for this story.
Sunday night, another symbol of youth beckons skywatchers the world over. A fresh-faced, day-young crescent Moon will hang in the western sky in the company of the planets Mars and Mercury. While I can’t promise a wrinkle-free life, sighting it may send a tingle down your spine reminding you of why you fell in love with astronomy in the first place.
Look low in the west-northwest sky Sunday evening April 19 to spot the day-old crescent Moon alongside Mars and returning Mercury. Brilliant Venus will help you get oriented. This map shows the sky around 40 minutes after sunset but you can start as early as 30 minutes especially if you’re using binoculars. Source: Stellarium
The Moon reaches New Moon phase on Saturday, April 18 during the early afternoon for North and South America. By sunset Sunday, the fragile crescent will be about 29 hours old as seen from the East Coast, 30 for the Midwest, 31 for the mountain states and 32 hours for the West Coast. Depending on where you live, the Moon will hover some 5-7° (three fingers held at arm’s length) above the northwestern horizon 40 minutes after sunset. To make sure you see it, find a location with a wide-open view to the west-northwest.
Earthshine gets easier to see as the Moon moves further from the Sun and the crescent fills out a bit. Our planet provides enough light to spot some of the larger craters. Credit: Bob King
While the crescent is illuminated by direct sunlight, you’ll also see the full outline of the Moon thanks to earthshine. Sunlight reflected off Earth’s globe faintly illuminates the portion of the Moon not lit by the Sun. Because it’s twice-reflected, the light looks more like twilight. Ghostly. Binoculars will help you see it best.
Now that you’ve found the dainty crescent, slide your eyes (or binoculars) to the right. That pinpoint of light just a few degrees away is Mars, a planet that’s lingered in the evening sky longer than you’ve promised to clean out the garage. The Red Planet shone brightly at opposition last April but has since faded and will soon be in conjunction with the Sun. Look for it to return bigger and brighter next May when it’s once again at opposition.
Diagram showing Mercury’s position and approximate altitude above the horizon during the current apparition. Also shown are the planet’s changing phases, which are visible in a telescope. Credit: Stellarium, Bob King
To complete the challenge, you’ll have to look even lower in the west to spot Mercury. Although brighter than Vega, it’s only 3° high 40 minutes after sunset Sunday. Its low altitude makes it Mercury is only just returning to the evening sky in what will become its best appearance at dusk for northern hemisphere skywatchers in 2015.
As an inner planet, Mercury goes through phases just like Venus and the Moon. We see it morph from crescent to “full moon” as its angle to the Sun changes during its revolution of the Sun. Credit: ESO
Right now, because of altitude, the planet’s a test of your sky and observing chops, but let the Moon be your guide on Sunday and you might be surprised. In the next couple weeks, Mercury vaults from the horizon, becoming easier and easier to see. Greatest elongation east of the Sun occurs on the evening of May 6. Although the planet will be highest at dusk on that date, it will have faded from magnitude -0.5 to +1.2. By the time it leaves the scene in late May, it will become very tricky to spot at magnitude +3.5.
Mercury’s a bit different from Venus, which is brighter in its crescent phase and faintest at “full”. Mercury’s considerably smaller than Venus and farther from the Earth, causing it to appear brightest around full phase and faintest when a crescent, even though both planets are largest and closest to us when seen as crescents.
Not to be outdone by the Venus-Pleiades conjunction earlier this month, Mercury passes a few degrees south of the star cluster on April 29. The map shows the sky facing northwest about 50 minutes after sunset. Source: Stellarium
Venus makes up for its dwindling girth by its size and close proximity to Earth. It also doesn’t hurt that it’s covered in highly reflective clouds. Venus reflects about 70% of the light it receives from the Sun; Mercury’s a dark world and gives back just 7%. That’s dingier than the asphalt-toned Moon!
Good luck in your mercurial quest. We’d love to hear your personal stories of the hunt — just click on Comments.
Hi everyone, I just wanted to apologize for the problem with comments we were having for the last month, there’s was an issue with our upgrade to WordPress 4.0. There was an incompatibility with our Theme, and then were having problems upgrading to the next version of the theme without taking the site offline.
Anyway, we were finally able to fix the problem and upgrade WordPress, our Theme and make comments work again.
I apologize for the disruption.
Fraser Cain
Publisher
Universe Today
P.S. But now that there’s a new theme, expect some more design changes. 🙂
As you might know, a few of us were attending Dragon*Con this weekend in Atlanta, where the Parsec Awards are held every year. Astronomy Cast has been up for a nomination every year, but we’ve always lost out to other folks like Star Talk and Planetary Radio.
Well, this year, we took a different tack and submitted our Guide to Space video series for the Fact Behind the Fiction category… and we won!
A big thanks and congratulations to my video co-creator, Jason Harmer as well as everyone else who has helped us write, edit, produce and shoot these videos: Susie Murph, Brian Koberlein, Chad Weber, Scott Lewis, Kevin Gill and Elizabeth Howell.
Since we started Universe Today almost 15 years ago, we’ve been entirely supported by advertising (and my savings). But now there’s an exciting new service called Patreon which allows fans to directly support the projects they love.
And if you’re a regular reader of Universe Today, you know we’ve got tens of thousands of articles, and a steady stream of podcasts, videos, graphics and interactive applications. We’ve got a pretty big team of writers and this stuff is expensive.
If you’re a serious fan of Universe Today, consider joining our Patreon community. You’ll get:
All the advertising removed from the website.
Early access to our upcoming videos.
Exclusive access to our full-length raw video interviews.
Hello Universe Today commentators! I just wanted to let you know that I’ve decided to disable Disqus comments on Universe Today, and return to plain old WordPress comments. There are a bunch of reasons why I decided to do this, most around my nervousness about having comments hosted outside Universe Today.
As you’ve probably noticed, I’ve struggled for years about what to do with comments on the website. I’ve tried lots of different plugins and services, searching for the right option. Continue reading “Back to Regular WordPress Comments”
If you’re an iPhone/iPad user, you might be interested to know that we’re giving away our Phases of the Moon app away for free today. That’s a $1.99 app, totally free.
Based on the amazing simulated lunar phases by NASA’s Goddard Spaceflight Center, this app allows you to spin through the phases of the Moon on your phone or tablet. You can pinch zoom to see a full lunar atlas, or pan the Moon. See what the phase of the Moon was on your birthday or some special event.
If you do install it, could you take a second and write a review? It would really help us out.
P.S. The Android edition has always been free, and honestly it’s better because of the sweet Live Wallpaper and Widget.
