The joy of early nights plus Curiosity’s ready to roll

Twilight length is determined by setting sun’s angle to the horizon. In late spring and summer in the northern hemisphere, it sets at a shallow angle and takes a long time to get far enough below the horizon for night to begin. In August, its steeper path means it’s out of the way sooner and night begins earlier. Illustration: Bob King

It’s nice to see the sky darker much earlier. Used to be we had to wait until 11:30 p.m. for the cover of night. If you spent just an hour outside with binoculars or telescope, you wouldn’t be in bed until 1 a.m. Earlier sunsets and shorter twilights are quickly putting an end to those sleepless nights. In the northern U.S. the sun now sets an hour earlier compared to late June and July, and the last trace of twilight is gone before 10 o’clock. Much more comfortable as long as you can keep your observing sessions to an hour or so.

Twilight has pleasures of its own like last night’s gathering of the moon, Saturn, Mars and Spica at dusk. Credit: John Chumack

Still, it’s tempting to take advantage of the earlier darkness and stay out longer under that beautiful summertime Milky Way. Fortunately or unfortunately, I often succumb to the temptation and once again find myself tiptoeing to bed at 1 a.m. Winter is the earnest amateur astronomer’s only solace, when super-early nights and bitter cold drive us back to the house before 10.

After wiggling its wheels in Martian soil yesterday, the Mars rover Curiosity will make its first test drive sometime today before heading out on a 1,300-foot jaunt to Glenelg.

Glenelg is the name given to a spot where three types of terrain intersect in an alluvial fan of debris left by ancient water flows. Plans call for Curiosity to drill into a section of layered bedrock there.  The rover will be driven remotely from Earth by a team of 16 human drivers. While Curiosity has an autonomous navigation mode enabling it to take pictures of the road ahead and command itself to avoid obstacles, its first treks will be guided by the human hand.

Watch Curiosity flex its wheels in this short video from Mars.

Though you and I could walk to Glenelg in less than 10 minutes, it will take Curiosity at least a month to get there. Not only will scientists be looking at other features of interest along the way, but they want to carefully and deliberately run the rover through its paces. Who can blame them for babying that brand new car?

Curiosity’s ultimate goal are the clay-laced foothills of Mt. Sharp shimmering through the pink haze five miles away.

The rover snapped a fisheye view of its first tracks today August 22. Credit: NASA/JPL-CalTech

Just released – photos of the rover’s first tracks on the Red Planet made today August 22. It moved forward about 15 feet, rotating 120 degrees and then drove in reverse for about 8 feet. Curiosity is now about 20 feet from its landing site, Bradbury Landing, named after science fiction writer Ray Bradbury. The Martian Chronicles is one of his best-known works.

Click HERE for another photo taken from a high-angle perspective.

Cosmonaut tosses satellite into orbit; farewell gathering of moon and planets tonight

Two planets, a bright star and the moon gather in the southwestern sky this evening August 21. Look about 45 minutes to an hour after sunset to see it best. Created with Stellarium

You’re invited to the farewell party tonight. Mars, Saturn, Spica and the moon will gather in a big, beautiful bunch one last time this year. Be sure you have a spot with a clear view to the southwest. The moon will be easy to see and will help you find the others. I always like to take along binoculars to add depth and extra snap to scenes like this one. Start looking about 45 minutes to an hour after sundown.

On September 18, when the crescent moon returns for a replay, Spica and Saturn will be lost in the twilight glow with only Mars remaining. Earth’s revolution around the sun causes all the stars and (sooner or later) planets to be swallowed up by the western horizon. Mars is close enough to Earth that its rapid orbital motion to the east helps it avoid sinking away in the west as quickly as the outer planets. Mars’ zip won’t help stay apace forever; Earth is faster yet and the Red Planet will finally disappear from the evening sky by late fall. Parting is such sweet sorrow.

Venus (left), Jupiter (top), along with the V-shaped Hyades star cluster (right of Jupiter) and Orion (lower right) light up the eastern sky at dawn earlier this week. Photo: Bob King

We’re blessed with two twilights – one at dusk, the other at dawn. Whichever one you spend your time with, you won’t go wrong. One could argue the morning version is even more stunning than the evening. Not only are Venus and Jupiter high and bright, but Orion and his starry belt climb above the trees, adding even more luster to the scene. If it’s inner peace you’re seeking, I recommend a dawn outing. Before the world revs up for another day, the sense of quietude can be profound.

Two frames from NASA-TV showing cosmonaut Gennady Padalka (at left with large backpack) using a lacrosse-like device to launch the small spherical satellite, a 20-lb. steel ball into space below and behind the space station. Click to see a video.

Gennady Padalka  had some fun yesterday while he and fellow cosmonaut Yuri Malenchenko were out for a little 7-hour spacewalk at the International Space Station. Besides moving a crane to a new location and installing a shield to protect the ship from micrometeroid impacts, he got to launch a satellite all by himself. You’ve got to see the video to appreciate how easy it was to launch – one quick push and the shiny steel ball floated away. To avoid any chance of it hitting the ISS, he aimed it behind and below the station.

We may have come a long way from the atlatlbut the concept of release by throwing from an extension of the human arm is similar. Clever humans.

The Russians will monitor the shiny ball from the ground to work on techniques for tracking space debris and its re-entry into our atmosphere. The little satellite will orbit Earth for about 3 months. It should be visible in binoculars; when more information on its orbit becomes available, I’ll post viewing times.

Sneaky auroras, ISS sunsets and awesome new Mars landing videos

Aurora rays, all lined up in a row, reach toward the Big Dipper (upper left) about 10:15 p.m. last night. Details: 20mm lens at f/2.8, ISO 1600 and 30-second exposure. Photo: Bob King

Last night the aurora paid an unexpected visit. A series of beautiful parallel rays stood tall in the northern sky between 10 and 10:30 p.m. (CDT). The display was brief and settled back into a quiet, greenish glow near the horizon for the remainder of the night. I was all ready to send out a tweet from my smartphone but unfortunately didn’t have service from the bog country.

By 10:45 p.m. the aurora had settled into a green-tinged arc low in the northern sky. Photo: Bob King

The space weather forecast had called for a slight chance of auroras from the effects of a coronal hole, an opening in the sun’s magnetic field that allows high speed particles to stream directly from the sun’s atmosphere into space.

When the probability is low, as it was last night, arctic regions will likely get an auroral display, but it’s hit or miss for the northern U.S. When I got back home and checked the  satellite data and Kp index it was clear there was a brief surge in northern light activity right at the time of my observation. Things quieted down by 11.

Auroras are again possible tonight from the same solar wind stream, so say NOAA’s space weather forecasters. Will we see the lights again? I hope so. Keep an eye on the northern sky as always just in case.

An anti-meteorite panel on the ISS. Credit: NASA

Russian cosmonauts Gennady Padalka and Yury Malenchenko aboard the International Space Station (ISS) will be installing additional anti-meteorite panels on the station today a 7-hour-long spacewalk. The panels are designed to protect the station from impacts by space debris.

The space station will be wrapping up a series of evening passes over North America later this week. Click HERE to find when it flies over your town. Last night we got a particularly dramatic flyby over the Duluth, Minn. region.

The space station fades from right to left as it passes under Vega in the constellation Lyra (outlined) last night about 10:23 p.m. Notice that its trail changes color from white to red as the station moves into Earth’s shadow. Photo: Bob King

The ISS rose up from the west, passed near the bright star Arcturus and climbed toward the top of the sky. At the very moment it shone brightest, the station quickly began to fade and soon disappeared in Earth’s shadow near brilliant Vega. Entering the shadow is the same as seeing the sun set from the perspective of the astronauts. As on Earth, also in Earth orbit. The ISS is bathed in the red glow of sunset or sunrise for about 10 seconds as it travels at over 17,000 mph. The color change from yellow to red was even visible with the naked eye. Since the craft circles Earth every 90 minutes, last night’s sunset was only one of 16 visible every 24 hours for the lucky astronauts.

Poof! Watch the dust cloud raised by crash of Curiosity’s heat shield
There’s more news from Mars including these two new videos taken by the Mars Descent Imager (MARDI) as Curiosity dropped to its landing in Gale Crater. The first shows the dust cloud raised by the impact of the heat shield. It’s nicely annotated so you can follow both the shadow of the shield and the flash of the shield itself before impact. The area in view is about 6/10ths of a miles (1 km) across.

The second video is even cooler and shows Curiosity’s descent. Keep an eye out at the end when the dust goes flying before touchdown! The rover also zapped its first rock – named “Coronation” – yesterday with a powerful laser. ChemCam hit Coronation with 30 pulses of its laser during a 10-second period. Each pulse delivered more than a million watts of power for about five one-billionths of a second creating a spark of vaporized rock. Spectrographs examined the flash and got the data needed to identify the rock’s mineral makeup. Read more HERE.

A ballgame played in the night sky

This map shows the sky facing west about 10 minutes after sunset tonight Aug. 19. The evening crescent moon swings low this time of year, making it easy to include it in landscape photos. Maps created with Stellarium

The moon’s back in the west tonight but very low especially from the northern U.S., where it sets about a half hour after sunset. Look for a wiry crescent around and shortly after sunset. Being so close to the horizon in twilight makes for good picture opportunities.

Tonight and the next couple nights are ideal for photographing the shapely moon in a pretty scene with trees or a favorite iconic building. Even a cellphone camera’s up to the job. There’s plenty of light to go around in the hour after sunset – give it a try.

I’ve co-opted the Great Square as a baseball diamond in this view. You’ll find the diamond in the eastern sky around 10 p.m. local time. Each baseline is a fist and a half  held at arm’s length long.

As a kid, I used  to play baseball with my buddies at a nearby park every summer. Listened to it on the radio, too. Now I mostly photograph our local teams for the newspaper and catch the highlights on TV. Still, whenever August comes around and the Great Square of Pegasus climbs the eastern sky at nightfall, I can’t help but think of that dusty baseball diamond of my youth. Like the real thing, the Square is plenty big. Each side is about 15 degrees across or about a fist and a half held at arm’s length. It’s hard to miss.

The stars or players in Pegasus have traditional Arabic names: Scheat (SHE-at), Matar (MAH-tahr), Markab (MAR-kab), Algenib (al-JEN-nib) and Alpheratz (AL-fer-rats).

I’ve marked some of the key positions on the diamond but it does have its deficiencies – no pitcher or any obvious outfielders. That’s OK. In lean times we’ve learned to make do.

At least each player has a name. While constellations have Greek and Roman names, most individual star names come from the Arabic peoples.  Scheat (the shin), Matar (lucky rain), Markab (the horse’s shoulder), Algenib (the side) and Alpheratz (navel of the mare) are our players’ names.

Alpheratz, which officially belongs to the neighboring constellation Andromeda, is shared by Pegasus to complete the diamond. That’s appropriate given that Perseus the Hero flew to Andromeda’s rescue on the great steed.

Have a look the next clear night to see how the game’s going. Now matter how you picture the Great Square, it’s as much a sign of the coming fall as the leaves changing on the trees.

Curiosity rover ramps up for road trip to Glenelg

A dry river spreads out to form an alluvial fan in southern Iran. Farms follow the curve of the fan. Credit: NASA

Hi-ho, hi-ho, it’s off to Glenelg we go! Scientists with the Mars mission have chosen Curiosity’s first exploration destination, a little place nicknamed Glenelg (after a village in Scotland) near the base of an  alluvial fan of sedimentary rocks, dirt and sand. Alluvial fans are common on Earth as streams flowing from mountains or canyons gradually spread out and deposit rocks and sand in great fans onto the flatter plains below.

Curiosity landed near the base of a similar fan-deposit on Mars; scientists will drive the rover further downhill to where the water might have collected. They’ll be looking for things like salts that are dissolved by water but later precipitate as solids when the water evaporates.

Curiosity’s first destination will be Glenelg, located at the intersection of three different types of terrain near the base of an alluvial fan. Later, it will pass through a natural opening in the dark dunes and wind its way to the foothills of Mt. Sharp. Click to enlarge. Credit: NASA/JPL

Glenelg. Notice anything peculiar about it? It’s a palindrome, a word or phrase that reads the same way in either direction. Fun examples include “kayak”, “evil olive”, “tangy gnat”, “radar” and “Oh, cameras are macho”. NASA folks selected Glenelg because the rover will be visiting the area twice – both coming and going – before it turns around and heads to the base of Mt. Sharp. Having a sense of humor makes any job more fun.

ChemCam Principal Investigator Roger Wiens, of Los Alamos National Laboratory, tests the rover’s ChemCam by observing the light from a plasma ball induced by the laser hitting a sample rock from a distance of about 10 feet. The laser beam itself is invisible. Credit: NASA/JPL-Caltech/LANL

The rover will travel 1,300 feet (400 meters) to the east-southeast of its landing spot to reach Glenelg; its first drilling target will be a section of layered bedrock (likely sedimentary rock deposited by or in water). Prior to departure, the team in charge of ChemCam will zap a 3-inch rock 10 feet away named N165 with a powerful laser. The resulting spark of vaporized rock will be examined with a spectroscope to determine the minerals that make up the rock. The rover will also exercise its wheels in the coming days before moving out.

The Milky Way courses from one end of the sky to the other in mid-August around 10 p.m. local time. The three brightest stars in the photo – Deneb, Vega (right) and Altair (bottom) form the Summer Triangle. Photo: Bob King

If one of your destinations is tonight’s sky, you’ll again be able to watch the International Space Station (ISS) fly by. I saw it unexpectedly last night making a brilliant pass across the northern sky. Most of the station’s passes continue to be in the north for the next few nights.

The times below are for the Duluth, Minn. region. For local times for your city, click over to either Heavens Above or Spaceweather’s Satellite Flybys.

I’d also like to point out that we’re now entering the best time of year for northern hemisphere sky watchers to enjoy the sight of the bright summertime Milky Way. This hazy band of light made of a multitude of stars crosses overhead from the W of Cassiopeia in the northeast all the way to the southern horizon. While the moon is still “missing” from the evening sky, take a drive out to the countryside to relish a view of the galaxy we call home.

Space station viewing time for Duluth, Minn. and region:
Tonight Aug. 18 starting at 9:36 p.m. across the northern sky
* Sunday Aug. 19  at 8:45 p.m. in the north and again at 10:21 p.m. During the second pass the ISS rises in the northwest and dramatically fades as it enters Earth’s shadow near the bright star Vega.
* Monday Aug. 20 at 9:30 p.m. Near-overhead pass
* Tuesday Aug. 21 at 8:38 p.m. in early twilight and again at 10:14 p.m.
for a brief pass in western sky

Be there with Curiosity in this wicked interactive panorama

Take a look around Mars today when you have a few minutes. Click the photo for a spectacular 360-degree interactive panorama. Panorama photo by Andrew Bodrov with images by NASA/JPL

If you’ve ever wondered what it’s like to stand on Mars and look around in all directions, wonder no more. Click on the photo to view a high-definition, interactive panorama of the Martian landscape pieced together with photos made by Curiosity’s navigation cameras. Since the images were taken from atop the nearly 7-foot tall mast, you feel like like you’re on stilts as you gaze this way and that including over the top of the rover.

You can use your mouse to move from left to right and top to bottom. The big mound in one part of the image is 3.4 mile high Mt. Sharp at the center of Gale Crater. That’s the direction Curiosity will head once it’s ready to roll.

My favorite parts were seeing the sun in the sky for the first time and watching the lighting change as I turned “my head’ to look around. The panorama link above is a large version for maximum YOU ARE THERE effect. For a smaller version as well as panoramas made using imagery from previous rovers, click HERE.

My hat goes off to photographer Andrew Bodrov for creating the scene using NASA images. Thanks for taking us to Mars!

Start your Mars day with a little bit of sol

Curiosity inside Gale Crater photographed on August 12 by the Mars Reconnaissance Orbiter. The grayish-blue patches near the rover are the blast pattern from the sky crane descent stage. Click image for a monster version. Credit: NASA/JPL-Caltech/University of Arizona

If not kin, Earth and Mars are blood brothers. Both have ice, clouds, storms, volcanoes and desert landscapes to name a few traits in common. We also share similar tilts in our axes and days that are almost identical in length.

Notice I said ‘almost’. The Martian day is 24 hours, 39 minutes and 35 seconds long or 2.7% longer than Earth’s. To distinguish it from an Earth day, scientists call it a “sol”, the Latin word for sun. In previous Mars missions as well as this one, you need to know what time it is at your lander or rover site so you can take pictures and measurements in the light of day and beam them up to the Mars orbiters for relay back to Earth.

Artist’s concept shows the Curiosity using it ChemCam instrument to investigate the composition of a rock surface. ChemCam fires invisible laser pulses at a target. The instrument then views the resulting spark with a telescope and spectrometers to identify the chemical elements. Credit: NASA/JPL illustration

To keep track of day and night at both operating rover sites (Opportunity Rover is still in good health) the teams operating the probes must synchronize their work schedules with Mars time. They do this by using a 24-hour Mars clock where the seconds, minutes and hours are all 2.7% longer than the standard 24-hour Earth clock.

That’s right. Those 40 minutes of extra time in the Martian day are divvied up evenly across the day to create a convenient 24-hour clock where every second is ever so slightly longer than an Earth second.

Planning life around Martian sunrise and sunset for the Earth-bound comes with interesting and sometimes painful consequences. Mission controllers’ work schedules slip out of synch with Earth time by 40 minutes a day. Many of us start work at the same time every day of the week. Rover operators begin their shift 40 minutes later each day. Huh?

NASA/JPL ground controllers celebrate when they see the first images transmitted back from Curiosity after a successful landing on Mars August 5-6, 2012. They’ll soon be living on Martian time. Credit: NASA – Bill Ingalls

Let’s say Curiosity’s operator and I both start work on Monday at 10 a.m. Remember, he’s using a watch synchronized to Mars time and I’ve got a cheap Earth watch from Target.

The next day we both start work again at 10 a.m. according to our watches. Can you guess what happens? He shows up 40 Earth minutes late even though his watch reads 10 a.m. just like mine. By the end of the week, the rover driver starts work 4 x 40 minutes or more than 2 1/2 hours late. After 18 days, he’s coming to work at 9 p.m. Earth time and working a long, lonely night! Yet his watch still tells him he’s arriving to work on time at 10 a.m. Again, this is because Mars’ day is 40 minutes longer than Earth’s.

You can imagine how a Mars work schedule must wreak havoc with your personal life. A day shift soon morphs into an evening shift and then an overnight. One entire cycle – the number of days it takes to get back in synch with Earth time – takes 36.5 days or a little more than five weeks. These men and women are working days and night over that time. Getting a good night’s rest must have been challenging.

Garo Anserlian, master watch and clockmaker, devised the first watch to tell Mars time. A Mars day, called a sol, is divided into 24 hours like an Earth day but 40 minutes longer. Credit: NASA

So it was for scientists involved with the previous two Mars rovers, Opportunity and Spirit. To help keep everything on schedule without having to constantly translate from Earth time to Mars time, system engineers involved with those missions went on a hunt to find a watchmaker to build a Mars watch. Enter Garo Anserlian of Executive Jewelers in the little town of Montrose, California.

He took up the challenge, attaching tiny weights to clock innards, to lengthen an ordinary Earth second into a Martian one. Members of the rover team each got a custom watch geared to Mars time to help them plan daily rover activities. That was back in 2003-2004. Now Anserlian sells Mars watches to regular folks at $295 a pop. Check out his site if you’re interested.

A Mars watch for sale by Anserlian’s Executive Jewelers store. Credit: Executive Jewelers

While today is only Sol 10 for Curiosity, the 10th Mars day since the landing, it’s Sol 3,044 for the Opportunity rover which landed in January 2004.  I wondered whether the Opportunity Rover folks were still bound to Mars time after more than 8 years of the rover’s operation on the planet.  To find out I called D.C. Agle in the Jet Propulsion Lab’s (JPL) newsroom.

For the first 90 days of the mission, they lived like Martians but since then JPL’s worked out a “more livable” arrangement. With Curiosity, the team of scientists and engineers will also clock their days by the punishing Mars schedule for the coming 3 months.

Some of the scientists still wear the watches, but most are now using desktop Mars clocks or Smartphone apps. Agle uses the free NASA program called Mars 24 for PC or Mac. It’s a  Java application that displays Martian times for both Curiosity and Opportunity Rovers and a representation of the planet showing its current sun- and night sides. Get it HERE and feel (almost) like you’re living on Mars.  There’s currently no NASA Smartphone app for Mars time, but several others are available at online stores:

* Mars Clock and Mars Surface Times for iPhone, iPad and iPod Touch
* Martian Time for Android

A screen grab from NASA’s free Mars 24 program. You can now have you own Mars clock right on your computer desktop. Credit: NASA GISS

One last time tidbit. Many of us watched the final minutes of Curiosity’s thrilling descent to Mars last earlier this month. While it all seemed to be happening moment-by-tense-moment, the probe had already landed 14 minutes earlier. Done deal. It took radio communications traveling at the speed of light 14 minutes to make the trip back to Earth. To quote the late Johnny Carson: “That is wild stuff.”

Three planets and a smile at dawn

Venus right next to the moon just a minute or two before it was covered yesterday afternoon. The difference in brightness is striking. Venus was still visible with the naked eye at the time. Photo: Bob King

I hope some of you got to see Venus alongside the crescent moon yesterday afternoon. The view through binoculars was simply amazing.  Venus was brilliant compared to the dull moon. Though the moon was officially brighter — magnitude -9 vs. -4.5 for Venus — the planet’s surface brightness was far higher because it’s wrapped in clouds that reflect sunlight well. The moon in contrast is covered in charcoal-toned dust and rocks.

The difference between the two could not have been more profound. By the way, the moon was only brighter overall. What it lacked in surface brightness, it made up in surface area.

Perseid meteor shower activity is winding down, but I managed to catch a busy spell when I stepped out at 3:15 this morning. Four meteors including a sputtering fireball shot out of Perseus in just five minutes of looking up. Amateur astronomer John Chumack uses a low-light video camera to record meteors from his home in Dayton, Ohio. He compiled all the meteor images he captured over August 11-12 into a single video. Hit play to see 220 Perseids fly by in just 2 minutes!

Venus is far to the right of the sun and high in the dawn sky in August. On the 15th it reaches a maximum separation of 46 degrees from the sun as seen by an observer on Earth. Planets and sun not to scale. Illustration: Bob King

Venus reaches greatest elongation tomorrow (Aug. 15) when it’s as far off to one side of the sun as it can get. That means it rises well ahead of the sun and stands high in the eastern sky at dawn. For Duluth, Minn. the planet comes up at 2:30 a.m., fully 3 1/2 hours before sunrise. As seen from Earth, Venus is almost exactly 50 percent illuminated by the sun and looks like a little half moon in a telescope. When the planet is west of the sun and visible in the morning hours, astronomers say it’s at greatest western elongation. At greatest eastern elongation, Venus shines in the evening sky and its other half is lit. At “full” and “new moon” phases the planet is either nearly in front of or behind the sun and lost in the solar glare.

Mercury joins Venus and Jupiter to form a long arc of naked eye planets visible in the morning sky at mid-month. The map shows the sky tomorrow morning about 45 minutes before sunrise. Created with Stellarium

While you’re out admiring Venus, look much lower in the northeastern sky about 45 minutes before sunrise for yet another planet at greatest western elongation – Mercury. Mercury is farthest west of the sun (18 degrees) on the 16th and easy to see if you have a wide open view to the east. The moon helps point the way tomorrow morning.

See the crescent moon hide Venus this afternoon

A gravel bar in the shape of a crescent formed in Lake Superior at the mouth of the Lester River in Duluth recently. Photo: Bob King

The Perseid meteors still have some spunk! Observers worldwide reported a sharp rise in activity between 9:30 a.m. and 12:30 p.m.  CDT (when it was dark in Asia) Sunday. Rates hit over 100 meteors an hour during that time. A good show was still in progress last night, finally tapering off some during early morning hours today.

Crescents are everywhere. I was shooting aerial photos for the newspaper about a week ago. As we flew along the shore of Lake Superior I was paying more attention air turbulence than anything else. The plane seemed impossibly delicate as it pitched this way and that in the wind and heat. I looked out the window to follow our progress and moments  later spotted the most perfect crescent moon – a gravel bar at the mouth of the Lester River northeast of downtown. The sight quickly took my mind off the bumpy ride.

Later this afternoon, sky watchers across much of North America will see Venus covered or occulted by the real crescent moon. Finding the moon will be a little tricky. If you live in the Midwest it’s only 20 degrees high (two fists held at arm’s length) in the western sky when it happens around 3:30 p.m. (CDT). East Coast observers will have a tougher time with the moon only a few degrees high.  Exceptionally clear skies are required to see a thin moon so close to the horizon in the middle of the day.

Venus will hover right above the edge of the lunar crescent this afternoon August 13. This view shows the scene from Duluth, Minn. when the moon will be 20 degrees high in the west at the time. Created with Stellarium

Mountain states and the West Coast have the easiest time of it. When the occultation starts between 1 and 2 p.m. Pacific time, the moon will be 40 degrees high in the western sky. Take along a pair of binoculars to help you find it. Look for the crescent about 45 degrees or 4 1/2 fists to the lower right of the sun.

Use this map and table from Sky and Telescope to find your city along with the time when Venus disappears behind the moon. Remember that the times shown are Universal or Greenwich Time. Subtract 4 hours for Eastern Daylight Time; 5 hours for Central; 6 for Moutain and 7 for Pacific.

Venus is tiny half moon tomorrow as seen in a small telescope. The moon will take about a half minute to completely cover it. Venus reappears on the other side of the moon at 4:22 p.m. for Duluth. Created with Chris Marriott’s SkyMap

Go out 10 or 15 minutes before the occultation to find the moon either with your naked eye or with assistance from binoculars. Venus should be very easy to see nearly pinned to the moon’s pale white sunlit edge even in small binoculars. A small telescope will show the planet as a small half moon. Because it’s tiny and near maximum brightness, it will probably stand out better than the paler moon.

You may even be able to see Venus with the naked eye. For easterners unable to watch the occultation, all is not lost. You can still use the moon to find Venus in the daytime. Go out an hour earlier,  find the moon and look one moon-diameter above it to see Venus.

The last widely observed occultation of Venus by the moon happened on the morning of April 22, 2009. Both were crescents at the time. Notice how much brighter Venus is than the moon. Photo: Bob King

The moon’s orbital motion will carry it closer and closer to the planet until it takes that first bite. Since Venus has an actual shape and size as opposed to stars which are pinpoints even in large telescopes, it will take the moon nearly a half minute to completely cover it. About an hour later, Venus will re-emerge from behind the moon. Those times are also in the table if you scroll further down.  For Duluth, Minn. the hide-and-seek starts at 3:31 p.m. with Venus reappearing at the other end of the moon at 4:22 p.m. Disappearance and reappearance times for several other cities are shown below.

A Venus-moon-hawk “conjunction” at 11:30 a.m. today Aug. 13 when the moon was 2 degrees from Venus. Once I found the moon, Venus was relatively easy to see with the naked eye. Give it a try yourself. Photo: Bob King

Many of us will be at work when the occultation happens. Don’t tell my boss, but I’m going to sneak out for a few minutes around 3:30 with my binoculars. It’s not often you get to see the moon occult a planet in the light of day.

* Dayton, Ohio at 4:40 and 5:32 p.m.
* Chicago, Ill. at  3:37  and 4:29 p.m.
* Grand Forks, ND at 3:27 and 4:22 p.m.
* Denver, Colo. at 2:35 and 3:40 p.m.
* Seattle, Wash. at 1:07 and 2:23 p.m.

Perseid report, Curiosity spies old riverbed and winter arrives at dawn

A fainter Perseid meteor (around 2nd magnitude) streaks above a line clouds lit by light pollution early this morning August 12. Details: 20mm lens at f/2.8, ISO 1250 and 45 second exposure. Photo: Bob King

It’s not much of a Perseid photo, but it’s all I’ve got to show from last night. Conditions were far from ideal in Duluth for the peak of the Perseid meteor shower. Lots of high clouds snuffed out the fainter meteors. Around 1 a.m. as rates were picking up, heavier clouds rolled in and I had to call it quits. How did you fare?

Not that there weren’t some great meteors – I saw 26 during about two hours of casual viewing; a couple were as bright as Jupiter and some came in pairs one right after the other. All were white or yellow and moved swiftly. Despite clouds, this rate seemed lower than expected.

The graph shows the zenithal hourly rate (ZHR) of the Perseid meteor shower. It spiked on Saturday afternoon (U.S. time) and stayed at a fairly high level into the night. It’s dropping off now as Earth moves out of the meteor stream. Credit: International Meteor Organization

Observers submitting reports to the International Meteor Organization’s Perseid website reported a maximum of 97 meteors per hour around 1:30 p.m. (CDT) Saturday August 11. For observers in North America overnight activity dropped to around 70-80 per hour. These numbers are what an observer would see under ideal dark skies with the radiant overhead. It’s known in the trade as the ZHR or zenithal hourly rate and determined by applying a mathematical formula to each individual’s meteor count.

Meteor shower watchers use the ZHR to standardize observations made by many different observers under different sky conditions. The actual number of meteors seen is nearly always lower, which is why you have to take meteor shower predictions with a grain of salt. By the way, you can still go out tonight to watch the shower. Numbers will be lower but the late-comers will still put on a show.

The moon and Venus, joined by Orion and Jupiter, will sparkle up the eastern sky tomorrow morning at the start of dawn. This map shows the sky facing east about 90 minutes before sunrise. Created with Stellarium

I finally turned in when the moon and Jupiter put a glow in the clouds to the east. Tomorrow morning if you’re willing to risk losing a bit of sleep, the moon and Venus will make a handsome couple at dawn. They’ll be joined by Orion – yes, Orion! – Aldebaran and the V-shaped Hyades star cluster next to Aldebaran. All the winter stars are on the move in the morning sky, itching to replace those of summer and fall. Watch out, snow will be here before we know it.

A part of the wall of Gale Crater north of the landing site shot with Curiosity’s high resolution camera. A network of valleys formed by water erosion long ago carved the rim. The main channel (labeled) looks like an arroyo or dirt road and is 11 miles away. Click to enlarge. Credit: NASA/JPL-Caltech/MSSS

Mission controllers have been uploading new software into Curiosity’s “brain” the past couple days to ready it for roving and geological exploration. On the first leg of its Mars journey, all it could “think about” was making a safe landing and shooting the first photos. Now that that’s been accomplished, it’s time for baby to walk.

One of the more interesting recent images from the rover shows a channel in the rocky rim of Gale Crater where water once flowed. According to NASA: “This is the first view scientists have had of a fluvial system – one relating to a river or stream — from the surface of Mars. Known and studied since the 1970s beginning with NASA’s Viking missions, such networks date from a period in Martian history when water flowed freely across the surface.”

We’ve seen these water-carved channels from orbit many times, but a ground level view makes it easier to imagine a Mars soaked with streams, lakes and maybe even an ocean.