Observers in the northern U.S. and southern Canada should be alert for auroras tonight. The direction of the magnetic field has been mostly south for the past 8 hours, providing a nice linkage into Earth’s magnetic bubble. It’s cloudy in Duluth, Minn., but the Ovation oval plot (above) would indicate visible aurora low in the northern sky from northern MInnesota, Michigan’s Upper Peninsula and northern Maine around 11-11:30 p.m. CDT.
Most of us would consider Bootes the Bear Guard a spring constellation. That’s when it first appears in the eastern sky, following the tail of Ursa Major the Great Bear as the snow drifts recede. Come fall, Bootes (Boh-OH-tease) and its bright luminary Arcturus recline in the west within spitting distance of the Dipper.
Every evening I look up to check on the condition of the sky. Arcturus is either flashing happily or gone missing, hidden by clouds. Gazing up from Arcturus, it’s easy to trace out the remaining points of starlight that form the kite-like figure of Bootes. Like a kite let go, Bootes drifts away to the west as the night deepens.
The next clear night, follow the arc of the Dipper’s Handle to Arcturus and then work your way up and around to pick out the constellation’s fainter stars. If you now direct your gaze to a blank spot between Bootes and the end of the Dipper’s handle, you’ll be staring at the center of a remarkable nothingness, the Bootes Void.
Normally we talk about the presence of something in the sky in this blog, but today we’ll focus on absence. The Void, a roughly spherical realm of space 250 million light years in diameter, is virtually empty. Space is already empty enough. If the sun were shrunk down to the size of a grapefruit, the nearest star system, Alpha Centauri, would be 2,000 miles away. From there, it’s another 1,000 miles to the next closest, Barnard’s Star.
American astronomer Robert Kirschner discovered the void in 1981 as part of a survey to measure how fast distant galaxies were fleeing from one another as the fabric of space expands in the ever-widening wake of the Big Bang. Six years later, Kirschner and team turned up 8 galaxies in this vast volume of space centered 700 million light years from Earth. By the late ’90s only 60 galaxies were known, making the Void not as devoid of galaxies as originally thought.
Still, the wind blows through it like a ghost town. Considering that the average distance between galaxies in typically a few million light years, the Void should contain some 10,000 inhabitants. Where have they fled?
The Millenium Simulation will give you a feel for the large-scale structure of the universe. Enjoy the ride!
Galaxies are vast assemblages of stars, clusters, gas clouds and planets thousands of light years across. Their mass gives them considerable gravitational might, so they’re attracted to one another. Over the lifetime of the universe, galaxies congregate into strands, clumps and clusters. The surrounding space empties out like a parking lot at closing time and becomes a void.
The Bootes Void is no ordinary emptiness. It’s HUGE. Too big to have formed with the current lifetime of the universe say astronomers. That’s why it’s thought to have agglomerated from smaller voids that merged together to form one of the largest voids in the known universe, a so-called supervoid.
Galaxy clumping has amazing consequences for the large-scale structure of the universe. Astronomers think the visible matter of the universe clustered around clumps of dark matter, which makes up 73% of all the ‘stuff’ out there, shortly after the Big Bang. Once galaxies formed, they continued their clustering ways up to the present day. Instead of a random distribution of matter across space, the universe looks like a sponge where hundreds of billions of galaxies swirl in filaments and nodes around the comparatively empty voids.
Funny how the biggest things in the universe can be so surprisingly close to home. Look up toward the Big Dipper and Arcturus in the western sky after sundown and think of where you are.
Looked at Mars lately? If you haven’t I’m not surprised. It’s lost it’s luster since spring and rides the “low path” in Scorpius in the southwestern sky at dusk. From my home in the mid-northern latitudes, it now spends most of its brief nightly circuit hidden behind trees. But I encourage you to look for the Red Planet over the next few evenings. It’s passing very close to a fascinating star in the head of Scorpius the scorpion, Delta Scorpii.
Delta, also known by its Arabic name, Dschubba (JOOB-a), normally shines at magnitude 2.3, a tad fainter Beta Scorpii (2.6) directly above it. But on June 26, 2000, amateur astronomer Sebastian Otero of Buenos Aires noticed something peculiar. He’d been making brightness estimates that night of stars that are constant or don’t vary in brightness.
To his surprise, when he selected Delta, he found it brighter than normal. After alerting others to confirm his result, observers around the world watched as the star slowly rose in light until peaking at magnitude 1.6 in 2003. Yes, three years later.
I got in on the fun, too, watching Dschubba outshine every star in its constellation except the brightest, Antares. The change in the appearance of the scorpion’s head was striking. It still is. While the star has fluctuated in brightness since Otero’s discovery, it remains unusually bright; current estimates place it around magnitude 1.8. And now Mars will take you right to it.
Delta’s an amazing star despite its unremarkable appearance. Nearly 15 times more massive than the sun and located about 470 light years from Earth, it’s blazing surface shines at least 14,000 times brighter than the home star. If those aren’t superlatives enough, this star rotates at least 112 miles per second, 90 times the sun’s rate.
Studies reveal the star is disrobing right in front of our eyes, flinging mass from its equator as it spins at breakneck speed. The material accumulates in a disk around the star and is responsible for the rise in brightness and appearance of bright lines of emission in the star’s rainbow spectrum.
Dschubba has three companion stars in orbit about it. One, a cooler, fainter star with a period of 10.8 years, may be connected with the Delta’s outburst in 2000 and a second peak in brightness in 2011. Perhaps its revolution about the primary star stirs the great beast to release extra material every 11 years.
While Delta Scorpii lays low this time of year, you can still follow it into October and then watch with anticipation when it returns to the morning sky in winter. If you’d like a chart with magnitudes to estimate its brightness, click over to the AAVSO and key in Delta Sco in the “Create a finder chart” window.
Site J it is! European Space Agency scientists have selected a safe but intriguing region on 67P/Churyumov-Gerasimenko for humanity’s first-ever soft landing on a comet. Site C, located on the larger ‘body’ of the comet, was selected as backup.
Choosing a landing site hasn’t been easy. Safety was a prime concern. Site J appears to have relatively few boulders and receives sufficient daily sunlight to recharge Philae and continue science operations on the surface beyond the initial battery-powered phase. The majority of slopes there are sloped less than 30º relative to the local vertical, reducing the chances of Philae toppling over during touchdown. The J Site also allows the probe to be in regular communication with the orbiter as it passes overhead during each orbit of the comet.
“As we have seen from recent close-up images, the comet is a beautiful but dramatic world – it is scientifically exciting, but its shape makes it operationally challenging,” says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.
Since the descent to the comet is passive in the comet’s low gravity field – like dropping a piece of paper – it’s only possible to predict the landing point to within about 1,000 feet (~300 meters). Descent time to the surface is estimated at 7 hours. Landing has to happen by November before 67P/C-G becomes too active spewing dust and gas as it draws ever nearer the sun.
“There’s no time to lose, but now that we’re closer to the comet, continued science and mapping operations will help us improve the analysis of the primary and backup landing sites,” says ESA Rosetta flight director Andrea Accomazzo.
Seeing this makes me feel like I’m in orbit. What a nice perspective with the comet in the frame. It was taken by the Comet Infrared and Visible Analyzer (CIVA) on September 7th and shows part of the spacecraft and one of its solar arrays from a distance of about 31 miles (50 km) from the comet.
CIVA is several instruments in one. CIVA-P consists of seven cameras – five regular cameras and one dual-instrument stereo camera – that will take a 360º panorama of the landing site once it’s safely on the surface of the comet. A section of the panorama will be shot in stereo. Landing is scheduled for November 11th.
CIVA-M has a miniaturized visible light microscope and a coupled infrared spectrometer (an instrument used to measure light in the infrared part of the spectrum) that will be used to study a drilled sample from the comet’s crust. CIVA-M is designed to identify organic materials in the soil.
Stephan Ulamec, Philae lander manager, will announce the primary and backup landing sites for the washing-machine-sized probe at a presentation tomorrow morning at ESA Headquarters in Paris. The challenges and scientific expectations of the sites will be presented and shared with the media. We’ll have photos and the latest information here when it arrives.
In the meantime, have fun exploring the huge mosaic of 67P/C-G snapped from just 17.3 miles (27.8 km) away. In the cropped closeup, there’s an interesting bright spot that may either be an artifact or a something reflective (ice?) in the foreground. Take a look at the image below, which I’ve lightened up to show the comet’s neck in reflected sunlight and a speckling of either “noise” from cosmic ray hits or a mix of noise and reflections from bright ice and dust particles released by the comet.
Feeling disappointed in the aurora last night? The storm happened as forecast only it petered out just about the time the sky was getting dark across much of North America. Observers in Maine caught a good show early, and the lights even put in an appearance here in northern Minnesota, albeit low in the north from behind clouds.
NOAA space weather forecasters call for minor G1 storm tonight September 13 from about 10 pm to 4 a.m. Central Daylight Time tomorrow.
Minor usually means auroras in the bottom half of the northern sky for skywatchers living in the U.S.-Canada borderland region. You may choose to ignore the forecast and go to bed. I understand. You’re feeling a little burned. Those who feel like soldiering on, remain alert for possible auroras.
It’s hard to blame NOAA. Predicting the magnetic inclination of a cloud of solar plasma at a distance is fraught with uncertainty. We get a little help from the Advanced Composition Explorer (ACE) which orbits at the L1 libration point, one of five places near Earth where the sun’s and Earth’s gravity are in balance, allowing a satellite placed there to remain relatively stationary. ACE pivots about some 932,000 miles (1.5 million km) from Earth and 92 million miles (148.5 million km) from the sun.
The probe detects the direction, strength and magnetic field particulars of incoming blasts of particles from the sun and provides advance warning of about one hour of dangerous storms. Storms that affect power grids, satellites and of course paint the sky in northern lights. It also measures the magnetic properties of the cloud and relays that data in real time for us to see in the ACE plots.
Yesterday’s big puff of electrons and protons came packaged in a magnetic field that linked into Earth’s - at first. But later in the evening, the cloud’s magnetic field changed from south to north and was effectively cut off from connecting with our planet’s magnetic bubble. Earth gave it the cold shoulder, and you and I lost some sleep.
After tonight, calmer conditions are expected for a couple days. After that, it’s anyone’s guess. I’ll be watching tonight and report back.
You’ve seen it looming in the background of so many photo for more than two years. Finally, we’re there. NASA’s Curiosity rover rolled up to Mount Sharp in Gale Crater. With a peak 2.7 miles (4.4 km) high, Mt. Sharp stands more than a half mile higher than Mt. Ranier in Washington.
The mountain is built of layer upon layer of stratified rocks deposited by water and wind after the massive impact that excavated Gale Crater more than 3 billion years ago. From orbit, scientists have detected clays in some of the layers, an indication that water flowed here in the past.
As Curiosity begins its trek up the mountain’s slope, it will first trundle across the Pahrump Hills, a region of layered rocks that’s part of the Murray Formation. At some point within this broad expanse of soft rock, the rover will drill a sample and analyze it before continuing upslope. Several miles later, it will encounter a ridge of hematite-bearing rocks. Hematite is a gray version of iron oxide (rust) that precipitates in hot springs or in pools of standing water.
An intriguing layer of clay-bearing rocks that lies further upslope and offers the best opportunity of finding organic, carbon-containing minerals. A region containing sulfates, found earlier by Curiosity in the form of gypsum (calcium sulfate) extends beyond the clay layer higher yet. Gypsum is the same material used to make drywall back on Earth.
Scientists hope to study the transition between the two. Sulfates point to a time when the ancient, more watery Mars evolved from a wet, fresh-water climate to a drier one with acidic waters that favored the formation of sulfates instead of clays.
We all hope Curiosity’s wheels, poked and torn by sharp rocks, will be up for the long journey ahead.
“In late 2013, the rover team realized a region of Martian terrain littered with sharp, embedded rocks was poking holes in four of the rover’s six wheels. This damage accelerated the rate of wear and tear beyond that for which the rover team had planned. The team altered the rover’s route to a milder terrain, bringing the rover farther south, toward the base of Mount Sharp”, according to NASA.
Curiosity has already fulfilled its initial goal of determining whether Mars ever offered an environment suitable for the formation and development of early life. Clay-bearing rocks in the Yellowknife Bay site revealed an ancient lakebed that once lapped with fresh water and contained the key elemental ingredients for life - sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon – as well as a sulfate energy source potential life could use to thrive.
(Scroll down for the latest update)
Just came in from a check on the northern lights and they’re out. Just a quiet start, but I can see a classic green arc low in the northern sky. Once my eyes were dark adapted, faint rays streaked the sky above the arc. No doubt they would have stood out more boldly were it not for the rising gibbous moon off to the east. Stay tuned for more updates during the night.
Here are some links for you to check out to help you plan through the night:
* 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.
* 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 it drops into the negative zone that’s good! A prolonged stay at -10 or lower increases the chance of seeing the aurora.
* UPDATE 8:15 a.m. Saturday Sept. 13: Well, well, well. Yes, the effects of the solar blast did arrive and we did experience a G3 storm, only the best part happened before nightfall had settled over the U.S. and southern Canada. The peak was also fairly brief. All those arriving protons and electrons connected for a time with Earth’s magnetic field but then disconnected, leaving us with a weak storm for much of the rest of the night. More activity is expected tonight but the forecast calls for a lesser G1 geomagnetic storm.
* UPDATE 10:30 p.m. : Although the aurora has died back, I just got the NOAA forecast update which still calls for a strong storm overnight. Crossing my fingers it happens.
* UPDATE 9:30 p.m. : Definite aurora seen through breaks in the clouds low in the northern sky here in Duluth, Minn. After a big surge late this afternoon and during early evening, activity’s temporarily dropped off. The ACE plot has “gone north”. Will keep tabs and report back.
* UPDATE Friday 7:30 p.m September 12: Wow! Kp=7 (G3 storm). Auroras should be visible now over the far eastern seaboard of Canada including New Brunswick and the Gaspe Peninsula. If I were a betting man, folks in Maine should see at least a low, glowing arc in the northern sky. Still dusk here in Duluth.
* UPDATE Friday 3 p.m.: The Kp index is now at “5″ or minor storm. If you live in the Scandinavian countries or Iceland, you’re getting a very good show right now.
* UPDATE Friday 9 a.m. September 12: Auroras did appear as forecast overnight beginning at nightfall and continuing through about 1 a.m. this morning. Then the action stopped. The Kp index reached “5″ during that time leading to a G1 or minor geomagnetic storm. It wasn’t a particularly bright aurora, remained low in the northern sky and had to compete with moonlight, so many of you may not have seen it.
The stronger G3 geomagnetic storm from the second and more Earth-directed solar blast is still forecast for tonight. This should bring a much better display and should begin right at nightfall. Peak is expected between 10 p.m. and 1 a.m. Central Daylight Time.
My forecast is good, so I’ll be updating during the night. Good luck and clear skies!
(Click HERE for updates))
Two bursts of solar particles propelled by flares on September 9th and 10th are expected to arrive starting tonight and possibly touch off a moderate G2 geomagnetic storm. Translation: auroras may bloom in the next few nights!
A moderate M4 flare occurred early on September 9th followed by a more powerful X1.6 yesterday afternoon. Provided the magnetic field the particles come packaged in points in the right direction – south – these bursts have good potential for creating auroras tonight and again over the weekend.
The timing is good because the moon is past full and won’t be too bright. During a moderate storm, auroras are often seen across the northern tier of states and Canada. According to the latest NOAA space weather forecast, activity should kick up but remain shy of storm level from 9 p.m.-midnight Central Daylight Time tonight September 11th.
The brunt of the storm is expected from 1-4 a.m. tomorrow morning the 12th with effects lasting until 7 a.m.
This may only be the start of an even stronger storm anticipated Friday night and continuing into the weekend beginning from yesterday’s flare. That one blasted material directly toward Earth. Always a good omen for auroras.
As always with northern lights, keep in mind they’re fickle. Most of the time, Earth’s magnetic defense – a humongous, teardrop-shaped bubble of magnetism called the magnetosphere – acts as a bulwark against strong solar winds, letting them slide by harmlessly. We’ll see what happens on this round, but I’m optimistic.
The Earth weather forecast for my locale is mostly clear tonight, so I’ll be monitoring the sky. Stop back later for an update.
* UPDATE 9 p.m. CDT: Quiet so far. Auroras still holed up in Hudson Bay and Quebec. The magnetic field direction of the arriving wind from the sun shows a lot of variation (see ACE satellite plot, topmost graph showing Bz) rising and falling from positive to negative. Negative is good! A prolonged stay at -10 or lower increase the chance of seeing the aurora.
Once you’re done chuckling, we’ll move on. Ahem!
If you’ve ever had trouble finding the remote planet Uranus, Luna can help you tonight. The waning gibbous moon will occult or cover up the planet for observers in northeastern North America, Greenland, Iceland and northern Scandinavia around 8 p.m. Eastern Daylight Time this evening.
If you have a small telescope, you’ll be able to watch the bright eastern (left) edge of the moon slowly approach and then hide the planet. Unlike a point-like star, which winks out in a split second when covered by the moon’s edge, Uranus shows a small disk and will fade more gradually over several seconds.
But let’s say like me you live outside the occultation zone. What will we see? From the Midwest, Uranus will be just less than 1° to the west (right) of the moon as it comes up in the eastern sky in late twilight. Over the hours, it will appear to move gradually drift to the west away from the moon as the moon moves eastward in its orbit.
The farther west you live, the farther Uranus will be from the moon’s western edge. But not too far. Even from the California Coast, Uranus strays only about 2° (four moon diameters) to the right of the moon.
The planet may even be easier to see in binoculars from points west because it will be further from the lunar glare. No matter what, it’ll be easy to find the planet, which shines around 6th magnitude.
Remember, you’ll need 50 mm binoculars, or better, a small telescope, to view the planet near the moon. Telescope users are encouraged to crank up the magnification and see Uranus’ diminutive disk next the moon, which appears gigantic in comparison. In reality, the 7th planet is nearly 15 times as large.
Get ready for an even better shot at seeing Uranus. On the morning of October 8th, the full moon will be in total eclipse and the planet will lie very close due east. With no glary moonlight and everyone focused on the eclipse, more people will probably see Uranus at one time than perhaps any time in history.