Feel the bliss, don’t miss Thursday’s partial solar eclipse

The solar crescents show how much Sun will be covered at maximum for various locations across the U.S. and Canada during the October 23rd (Thursday) partial solar eclipse. Credit: Jay Anderson

Doing anything Thursday afternoon? Have a few minutes to spareThere’s a partial eclipse of the Sun visible across much of North America and of Mexico you might like to catch. For observers in the U.S. and Canadian West the whole event begins and ends in the afternoon before sunset. Those living east of the Great Plains will see the Sun set while still in eclipse.

During a solar eclipse, the orbiting Moon passes between the Sun and Earth, completely blocking the Sun from view as shown here. In Thursday’s eclipse, the moon will pass a little north of a line connecting the three orbs, leaving a portion of the Sun uncovered. To view a partial solar eclipse, a safe solar filter is necessary. Credit: Wikipedia

Solar eclipses occur when the Moon glides between the Earth and the Sun, temporarily blocking it from view. Total solar eclipses get most of the attention because the Earth- Moon-Sun alignment is perfect. Like a snug lid on a pot, the Moon blanks out the Sun completely to create a dramatic spectacle of a black, fire-rimmed disk set in a plush solar corona.

Partial eclipses happen because the Moon’s orbit is tipped a few degrees to the Sun-Earth line. Most months, it passes north or south of the Sun and misses it completely. But during a partial eclipse, the Moon’s close enough to that line to partially block the Sun from view. Unlike a total eclipse, all phases of a partial eclipse are unsafe to view unless you use a safe solar filter or view it indirectly via projection.

Map showing times and percentage of the Sun covered during Thursday’s partial solar eclipse. Times are Pacific Daylight – add 1 hour for MDT, 2 hours for CDT and 3 hours for EDT. Interpolate between the lines to find your approximate viewing time. The arc marked A shows where the eclipse begins at sunset; B = Maximum eclipse at sunset and C = Eclipse ends at sunset. Credit: NASA, F. Espenak,with additions by Bob King

As you can see from the map, nowhere will this eclipse be total. Maximum coverage will happen in Nunavut Territory in northern Canada where the musk oxen might catch sight of a fat solar crescent 81% covered by the moon at sunset. The farther north you live in the U.S. or Canada, the deeper the eclipse. Northern U.S. states will see around 60% covered compared to 40% in the deep south. To find out when the particulars for the eclipse for your city, use these links:

* U.S. Cities
* Cities in Canada and Mexico 

Some of the different kinds of safe solar filters available. They work by reflecting or absorbing most of the light from the Sun, allowing only a fraction through to the eyes. NEVER LOOK DIRECTLY AT THE SUN without one. Click photos for a supplier of eclipse glasses. Credit: Bob King

Solar filters come in a variety of styles from inexpensive eclipse glasses that use an optical polymer to glass welder’s filters to caps you place over the front end of a telescope. It’s important to use the correct kind – don’t stack a bunch of sunglasses and figure “it’ll do” or look through smoked glass. They still allow dangerous UV and infrared light to pass through and will mess up your retinas for life.

Because we’re on the heels of the eclipse, if you don’t already have a pair of eclipse glasses I recommend a #14 welder’s glass. It’s my favorite actually because it’s easy to stuff in a pocket and heavy-duty enough to take a few dings. You can pick one up for a few dollars at a welding supply shop. Only buy a #14 – lower numbers won’t cut it.

A piece of aluminum foil, a pin and a cardboard box are all you need to build a pinhole projector. The tiny hole creates a small image of the eclipsed Sun inside the darkened box which you place over your head.

Projection provides a fine alternative to using a filter. You can mount a pair of binoculars (or small telescope) on a tripod and project the Sun’s image on a sheet of white paper or build your own pinhole projector using the instructions above.

You can mount binoculars on a tripod, cover one lens with a lenscap and project the sun’s image safely onto a sheet of white cardboard. Credit: Bob King

If leaves still cling to your trees this season, the narrow spaces between the leaves act like natural pinholes and will cast multiple images of the eclipsed Sun on the ground below.

You can even place one hand atop the other and let the sun shine through the gaps between your fingers to see the eclipse. Low tech as it gets, but works in a pinch.

Here are some other things to watch for during the eclipse:

* If you live where half or more of the sun will be covered, you may notice a change in the quality of daylight. To my eye, the light becomes “grayer”. What do you see?

* Telescope users will see the mountains and crater rims along the moon’s edge as tiny bumps and projections against the brilliant solar photosphere. You’ll also notice how much blacker moon is compared to sunspots. Guess what? We’ve got a huge sunspot out there right now – Region 2192. Perfect for comparison!

Partially eclipsed sun just before sunset seen from Island Lake north of Duluth in May 2012. Credit: Bob King

*  Those living where parts of the eclipse happen at sunset will get an extra special view of the sun with a big bite out of it right sitting atop the southwestern horizon.

I wish you excellent weather – good luck!

 

Total lunar eclipse – what a beauty!

The moon just coming out of eclipse over Spring Lake north of Duluth, Minn. this morning October 8. Details: 200mm telephoto, ISO 800, 1 second exposure. Credit: Bob King

I hope your sky was clear for the total lunar eclipse. It sure wasn’t here. A big bank of clouds moved in before totality. I was shocked when I looked at the window to see a clear sky in the east and not a single star – or moon – in the west. That’s why man invented the car.

Moon around mid-totality with the planet Uranus (left) for company. Credit: Bob King

25 miles north of town the burnt orange moon slid out from under the clouds. It was already mid-eclipse, but no matter. I pulled over to the side of the road to enjoy the sight as twilight crept up from behind.

In binoculars Uranus was plain to see near the lower edge of the moon where the color was deep, rich and red. Up along the lunar topside the color graded to a pale straw yellow.

The full moon departs Earth’s shadow over a spruce bog tinged with fall color north of Duluth Wednesday morning around 7 a.m. Credit: Bob King

Clouds threatened again sending me fleeing to a lake shore and finally another roadside. Around 6:30 a.m. traffic picked up. Everyone driving south or west on their way to work and school got the astronomical treat of their life – the moon emerging from total eclipse right out the front windshield. Sweet!

The partially eclipsed moon glows against Earth’s setting shadow (the purple band) this morning. Full moons are directly opposite the sun, setting around sunrise and rising at sunset. When you look at the moon during eclipse you’re staring directly down the shadow cone cast by the planet. Credit: Bob King

For a total lunar eclipse to happen, the moon must be full and lie in the same plane as Earth’s orbit. Since the moon’s orbit is tilted 5°, it normally misses Earth’s shadow at full, passing a few degrees above or below it.

The moon partially covered in Earth’s shadow seen from Dayton, Ohio this morning. At the moon’s distance, the planet’s shadow is surprisingly small – only big enough to cover the Seven Sisters (Pleiades) star cluster. Credit: John Chumack

The full moon orbits behind the Earth opposite the sun; as the sun rises the moon sets. At the moon’s distance of 240,000 miles, the Earth’s shadow, both penumbra and umbra, spans a little more than 2° or about the size of the Pleiades star cluster.

Seems pretty small, doesn’t it?

But viewed from the ground, Earth’s shadow reaches from one end of the western horizon to the other. In the evening, the shadow is equally broad but appears in the eastern sky. This morning we had the unique opportunity to see the partially eclipsed moon in Earth’s distant shadow at the same time as seeing the much bigger near-shadow of the planet. Wild thought.

Full sequence of this morning’s total lunar eclipse. Details: Canon 6D camera, 80mm refractor, 2-second exposure at ISO 6400. Credit: John Chumack

Anticipating Wednesday’s awesome lunar eclipse

Watch for a ruddy moon in Pisces the Fish during the total lunar eclipse which happens Wednesday morning October 8th. The moon’s color can range from dark brown to coppery red depending on the transparency of the Earth’s atmosphere as described below. This map shows the view at the start of total eclipse as seen from the Midwest. Source: Stellarium

If you missed last April’s total lunar eclipse because of weather or commitments, you’ve got a second chance Wednesday morning October 8th. This is the final total lunar eclipse of 2014 and the second of four in a series called a tetrad – four consecutive total eclipses occurring at approximately six month intervals this year and next.

On Wednesday morning October 8, the moon will slide into Earth’s shadow and we’ll be treated to a total lunar eclipse. The outer shadow or penumbra only lightly shades the moon; for most of us the eclipse begins when the moon touches the inner, darker shadow called the umbra. Times are shown for each stage of the eclipse. Add one hour for EDT, subtract one hour for MDT and two hours for PDT. Credit: NASA / F. Espenak with additions by Bob King

“The most unique thing about the 2014-2015 tetrad is that all of them are visible for all or parts of the USA,” says longtime NASA eclipse expert Fred Espenak.

This eclipse happens during the early morning hours, so North American skywatchers will need to remember to set their alarm clocks. In the Midwest, partial eclipse begins at 4:15 a.m., when the moon’s eastern limb eases into Earth’s umbral shadow.

World map showing where the eclipse will be visible. Most of North America and much of Asia and Australia will see the event. Those living in the western half of the U.S. will see the eclipse from beginning to end. Farther east, the partially eclipsed moon sets at sunrise. Credit: NASA / F. Espenak

Earth’s shadow is composed of two nested components – the inner umbra, where the Earth completely blocks the sun from view, and an outer penumbra, where the planet only partially blocks the sun. Because the penumbra is a mix of shadow and sunlight, it’s nowhere near as dark as the umbra.

Animation showing the moon’s passage through the penumbra and umbra during the upcoming total eclipse. Credit: Tom Ruen

A lunar eclipse is divided into stages beginning with the moon’s entry into the penumbra. Most of us won’t notice any shading on the moon until it’s well inside the outer shadow about a half hour before partial eclipse begins. Look for a subtle darkening along its eastern edge.

During a lunar eclipse, the sun, Earth and moon are neatly lined up in space. For a few hours, the orbiting moon passes through Earth’s shadow and we experience a lunar eclipse. Credit: Starry Night

Because the Earth is a solid object, it casts a shadow in sunlight just like you and I. A lunar eclipse occurs when the sun, Earth and moon are precisely lined up in a row at the time of full moon, and the moon moves into Earth’s shadow.

Although the moon’s doing all the moving, it looks like the shadow is encroaching on the moon, slowly devouring it nibble by nibble. When the moon’s about half covered you’ll notice that the shadowed half is deep red or orange.

Artist view of Earth totally eclipsing the sun as viewed from the moon. Low angled sunlight filtered by our atmosphere is reddened in exactly the same way a setting sun is reddened. That red light bathes the moon’s surface which reflects a bit of it back toward Earth, giving us a red moon during totality.

Sunlight filtered and bent by Earth’s atmosphere spills into the umbral shadow and colors the moon a coppery red, burnt orange or rust. You can picture why this happens by pretending you’re standing on the moon looking back at Earth during total eclipse.

From your new perspective, the Earth passes in front of the sun, ringed by a glowing, red-orange atmosphere. Our atmosphere bends or refracts the light from all the sunrises and sunsets around the planet’s circumference into the umbra, adding color to the moon.

Depending on the amount of suspended particles called aerosols in Earth’s atmosphere at the time, the moon’s disk can glow a bright copper orange to deep brown-black. The more particles and haze, the greater the light absorption and darker the moon.

For the East Coast, totality begins during bright twilight with the moon low in the western sky. Skywatchers in the central U.S. will see all of totality and most of the final partial phases before moonset. If you live in the western U.S. you’ll get to watch the whole shebang in a dark sky.

Mid-eclipse is when the moon is deepest in Earth’s shadow. Since the top or northern end of the moon is closer to the shadow’s edge, it should appear noticeably lighter than the bottom half, which lies closer to the center.

The moon in mid-eclipse during the last total eclipse on April 14-15, 2014. You’ll notice a lot of variation of light and color across the disk. Credit: Bob King

After mid-eclipse, the moon slowly exits the Earth’s shadow and performs the whole show in reverse, transitioning back to partial eclipse and finally exiting the penumbra.

Besides the pleasure of seeing moon change color like a quickie version of fall, watch for the sky to darken as totality approaches. Eclipses begin with the sky flooded in bright moonlight nearly barren of stars. During totality, all the stars come back in a most breathtaking way. Be sure to sweep your gaze east to enjoy great views of the winter constellations including Orion.

A rare treat greets anyone with a pair of binoculars during next Wednesday morning’s total eclipse. The planet Uranus will sit a little more than one moon diameter to its southeast during totality. This view shows the scene from the U.S. Upper Midwest at 5;30 a.m. Source: Stellarium

By good fortune, the eclipsed moon will lie only about 1/2° west of the planet Uranus which should be easy to spot in binoculars during the hour of totality. Speaking of which, binoculars are a great way to enjoy the eclipsed moon. Somehow they give it a more three-dimensional look. Colors are richer and you’ll see the lunar disk suspended among the stars, a rare sight.

For your latest forecast, click HERE. I’ll have more information for you early next week including links for watching the eclipse on the web and photo tips. Stay tuned!

Lunar eclipse will give NASA moon orbiters the shivers

Artist’s view of Earth eclipsing the sun next Tuesday morning April 15 as seen from the Lunar Reconnaissance’s Orbiter’s perspective. For several hours, it and NASA’s LADEE dust explorer will be cut off from sunlight. Back on Earth, we see the moon slide into our planet’s shadow. Credit: NASA

While we’re all bundled up for next Monday’s late night total eclipse of the moon, NASA will be taking special precautions to ensure its two moon probes survive the deep chill they’ll experience when the moon dives into Earth’s shadow.

NASA’s LRO has been orbiting, mapping and studying the moon since 2009. Credit: NASA

The Lunar Reconnaissance Orbiter (LRO), launched in 2009, has spent the past four-plus years photographing and mapping the moon in great detail from an orbit dipping as low as 31 miles (50 km). One of its goals is to determine future lunar landing sites. The craft also examines the moon’s radiation environment and maps the concentration of hydrogen – the main ingredient of water – across the globe. Hydrogen “hot spots” imply potential locations of water ice beneath the surfade or bound to moon rocks.

LRO will orbit the moon twice in Earth’s shadow. All instruments will be shut down since they would otherwise drain the batteries which can’t recharge without sunlight. Credit: NASA

LRO depends on sunlight to keep its batteries charged and instruments running. During the upcoming lunar eclipse, the moon will be either partially or fully within Earth’s shadow for several hours. With no sunlight reaching the probe’s solar panels, recharging the batteries isn’t possible.

To prevent damage to the either instruments or batteries, NASA plans to shut down all of LRO’s science instruments next Monday night for the duration of the eclipse. As soon as the event is over, the sun will slowly recharge the batteries and mission control will bring everything back online.

While LRO’s no stranger to eclipses,this time the spacecraft will have to pass through the complete shadow twice before the eclipse ends – longer than in any previous event.

“We’re taking precautions to make sure everything is fine,” said Noah Petro, Lunar Reconnaissance Orbiter deputy project scientist. “We’re turning off the instruments and will monitor the spacecraft every few hours when it’s visible from Earth.”


Understanding lunar eclipses

During other briefer eclipses, scientists have used the opportunity to study how the moon’s surface cools during these events, shedding light on the composition of the lunar crust. During the June 15, 2011 eclipse, temperatures on some areas of the moon dropped 180 degrees F compared to sunny, pre-eclipse conditions.

While LRO is expected to emerge from the shadow with flying colors, the forecast for NASA’s Lunar Atmosphere and Dust Explorer (LADEE) spacecraft is sketchy. The probe was never designed to withstand hours in the deep freeze of a shadowed moon.

“The eclipse will really put the spacecraft design through an extreme test, especially the propulsion system,” said Butler Hine, LADEE project manager.

Prior to impact on or before April 21, ground controllers at NASA’s Ames Research Center in Moffett Field, Calif., are maneuvering the spacecraft to fly approximately 1 to 2 miles (2-3 km) above the lunar surface to gather science measurements at the lowest altitude possible. Credit: NASA

LADEE (pronounced ‘laddie’) has been circling the moon studying dust in its extremely rarefied atmosphere since last fall. Much of the dust sputters off the surface during small meteorite impacts. If it survives the eclipse, LADEE will perform additional week of science before the mission is terminated. Rather than just shutting the probe off, mission control will direct it to crash into the moon near on or around April 21. LRO will locate study the impact site when it makes its next flyover a few months later.

Meanwhile, NASA invites you to  “Take the Plunge Challenge” and guess  what date LADEE will slam into the surface. Winners will be announced after impact and e-mailed a commemorative, personalized certificate from the LADEE program. The submissions deadline is 5 p.m. CDT tomorrow April 11.

For more information on the April 14-15 total eclipse of the moon including viewing times for your time zone, please see my earlier blog.

Brilliant Mars opening act for upcoming total lunar eclipse

Brilliant Mars shines atop dimmer Spica in the constellation Virgo in this photo taken Sunday night April 6. The planet now rises at sunset and is easy to spot around 9:30 p.m. in the southeastern sky. Yes, we still have almost 4 feet of snow here in Duluth, Minn. Credit: Bob King

Mars reaches opposition today, its closest approach to Earth since Dec. 2007 and the brightest we’ve seen it since 2012. What a sight it’s become. Last night, while walking our respective dogs, my daughter took one look at the gleaming pink-orange “star” in the southeastern sky and knew immediately it was Mars.

About every two years, Mars and Earth line up on the same side of the sun at opposition. Because Mars’ orbit is eccentric (less circular than Earth’s) the two planets are closer at some oppositions than others. This year’s opposition is a relatively distant one. Illustration: Bob King

While it sounds like an act of defiance, opposition refers to Mars being on exactly opposite side of the sky as the sun. The planet rises at sunset this evening and sets when the sun pops up tomorrow morning. Not only is Mars out all night long, but being opposite the sun, it’s paired up closely with Earth on the same side of the sun as shown above.


One full rotation of Mars on April 8 created by Tom Ruen. North polar cap at top.

That’s why Mars is so doggone bright – it’s close! Of course we know that’s a relative term in astronomy. Today the Red Planet is 57.7 million miles away, which sounds rather terribly far. But keep in mind that it can be up to 249 million miles away. So yes, Earth and Mars are practically neighbors … for a little while. The same orbital motions that brought them together will also move them farther apart in the coming months.

Now here’s the kicker. Because the orbits of Earth and Mars aren’t perfect circles, the two planets are actually closest on April 14, six days past opposition. That’s the same night as the total eclipse of the moon. Even better, the moon will only be a “fist” away from the planet. What a sight they’ll make – two red orbs aglow in the southern sky.

Mars outshines its neighbors Spica and Arcturus in the east and is ever so slightly brighter than magnitude -1.46 Sirius off to the southwest. The map shows the sky around 9:30 p.m. local time tonight. Stellarium

The Red Planet far outshines the nearby stars Spica and Arcturus and at magnitude -1.5 glows a hair brighter than Sirius, the brightest star in the entire sky. While similar in brightness, their colors are dramatically different. Compare the two and tell us what you think.

One side of Mars, the side turned toward the Americas during the best observing times this week, shows relatively few features. Use the map below to help you identify other dark markings as they rotate into view in the coming days and weeks. North at bottom. Credit: Mark Justice

Mars won’t appear bigger or brighter until its next opposition in May 2016 so take a look at this miniature “eye of Sauron” beaming in the south the next clear night.

If you have a telescope, use a magnification of 150x or higher to look for the planet’s very tiny north polar cap (it’s summer there and the cap has shrunk!) and other dark markings on its surface. This week, the planet’s “blank” hemisphere is presented for observers in the Americas. Be patient. The more obvious features like Mare Erythraeum, Syrtis Major and Mare Acidalium will soon rotate into view (see map below).

Complete Mars map showing many more features. Click to learn more about Mars’ upcoming opposition. Credit: Association of Lunar and Planetary Observers (A.L.P.O).

 

Seven ways to savor the upcoming total eclipse of the moon

Next Monday night April 14-15, skywatchers across much of North and South America will get to see a total eclipse of the moon. Lunar eclipses last for hours and can be safely viewed with the naked eye. This photo was taken of the June 2011 eclipse. Credit: Muhammed Mahdi Karim

It’s been too long. The moon last slipped into Earth’s shadow for North America in Dec. 2011. Next Monday night’s eclipse will end the current dry spell and make for a thrilling night out.

Map showing where next Monday night’s (April 14-15) eclipse will be visible. The western hemisphere has prime viewing seats. Credit: Fred Espenak

This eclipse is the first of four total lunar eclipses spaced about six months apart that will be visible across most of the Americas. The others occur on Oct. 8 this year, April 4, 2015 and Sept. 27, 2015. This particular sequence of four total lunar eclipses with no partials in between is called a ‘tetrad’. While we all hope for clear skies, if the weather’s uncooperative next week, you won’t have to wait long for another eclipse.


Eclipse tetrads explained

Lunar eclipses unfold slowly, lasting up to five hours. Unlike a total solar eclipse, where the sun disappears at most a few minutes, totality during a lunar eclipse can easily last more than an hour, giving you lots of time to enjoy the spectacle.

The only downside will be the late hour. Try to get some shuteye early as most of the eclipse happens after midnight in the wee hours Tuesday morning.

Because the moon’s orbit is tilted 5 degrees, the full moon normally misses the cone of shadow cast by the Earth and we see no eclipse. But several times a year, the moon’s orbit intersects Earth’s at the time of full moon and we see an eclipse. The Credit: Wikipedia

Lunar eclipses occur during full moon when the sun, Earth and moon line up in a neat row, and the moon passes into the shadow cast by our planet. You’d think eclipses would happen every full moon, but they don’t because the moon’s orbit around the Earth is tipped 5 degrees to Earth’s orbit around the sun.

The moon’s tipped orbit (red) is the reason we only get occasional eclipses at full moon. Most of the time the moon is either a little above or below the ideal alignment. Credit: Bob King

The moon spends most of the time above or below the plane of Earth’s orbit. And since Earth casts a shadow across its orbital plane, a lunar eclipse can only happen if the moon happens to be crossing that plane at the same time it’s full. That’s why eclipses are such a now and again thing.

While total solar eclipses are only visible along a narrow strip of land or ocean, a total lunar can be seen across half the globe wherever the sky is dark and the moon is up.

The moon’s past from west to east (right to left) across the dual shadow cast by Earth. The diagram shows key times (CDT) during the eclipse listed in the table below. Credit: Fred Espenak with additions by the author

Earth’s shadow is composed of two nested components – the inner umbra, where the Earth completely blocks the sun from view, and an outer penumbra, where the planet only partially blocks the sun. Because the penumbra is a mix of shadow and sunlight, it’s nowhere near as dark as the umbra.

An eclipse is divided into stages beginning with the moon’s entry into Earth’s lighter penumbral shadow. Most of us won’t notice any shading at all until about a half hour in, when the moon is deep enough inside to reveal a subtle darkening along its eastern edge. The table below lists the times for each stage of the eclipse across the four time zones:

Eclipse Events                     EDT             CDT                 MDT                PDT

Penumbra visible 1:20 a.m. 12:20 a.m. 11:20 p.m. 10:20 p.m.
Partial eclipse begins 1:58 a.m. 12:58 a.m. 11:58 p.m. 10:58 p.m.
Total eclipse begins 3:07 a.m. 2:07 a.m. 1:07 a.m. 12:07 a.m.
Mid-eclipse 3:46 a.m. 2:46 a.m. 1:46 a.m. 12:46 a.m.
Total eclipse ends 4:25 a.m. 3:25 a.m. 2:25 a.m. 1:25 a.m.
Partial eclipse ends 5:33 a.m. 4:33 a.m. 3:33 a.m. 2:33 a.m.
Penumbra visible  ——– 5:10 a.m. 4:10 a.m. 3:10 a.m.

During a total lunar eclipse (seen on Earth) an astronaut on the moon would instead see the Earth cover the sun, its atmosphere aglow with the combined light of all the sunrises and sunrises “leaking” around the rim of the planet. The light would bathe the moonscape in deep orange light. Stellarium

Partial eclipse begins when the moon treads within the dark umbra. Nibble by nibble the shadow eats away at the lunar disk. When only a sliver of the moon remains in sunlight, you’ll notice the shadowed portion glowing an eerie red or deep copper. To understand why, imagine an astronaut on the moon looking back at Earth during the eclipse.

During the next Tuesday morning’s eclipse, the moon will be just 1.5 degrees from Spica and not far from the planet Mars in the southern sky. Don’t forget to give Saturn a nod, located about two “fists” to the left of the moon. Stellarium

From her perspective, as the Earth passes in front of the sun, it’s surrounded by a glowing red-orange ring of light. Our atmosphere bends the light from all the sunrises and sunsets around the planet’s circumference into the umbra, coloring the moon red. Earth’s shadow isn’t really black after all but more a deep rusty red. Back on Earth, the moon will hang like a ghostly amber globe near the bright star Spica.

After mid-eclipse, the moon slowly exits the Earth’s shadow and performs the whole show in reverse, transitioning back to partial eclipse and finally exiting the penumbra.

Different aspects of a total lunar eclipse from start to near finish photographed in Hefei, China on Dec. 10, 2011. Credit: Reuters

You can take in the eclipse as casually as you like, but are seven cool things you might like to watch for:

#1 – When will you detect the first hint of penumbral shading? Keep an eye on the eastern (left) side of the moon for a “dented” appearance.

#2 – What color and how bright is the totally eclipsed moon? Depending upon the aerosol content of the atmosphere (greatly affected by volcanic eruptions), eclipses range from bright copper to dark brown and even black. Try rating this one on the traditional Danjon scale where “4″ is bright and “0″ is nearly invisible.

#3 – Watch for “the night within the night” phenomenon. If you thought it was dark out at the start of the eclipse, you’ll be amazed at how inky the landscape becomes during totality. As the eclipse progresses, the stars and Milky Way return to view.

#4 – With the entire moon darkened during totality, it will be relatively easy to watch it block or occult any star within its path. Many stars ranging from magnitude +8 and 12 will be occulted when viewed through small to medium telescopes. Click HERE for stars and times.

#5 – Binocular and telescope users should also look for a blue tinge to the encroaching umbral shadow as it slowly envelops the moon caused by light refracted by the upper atmosphere’s ozone layer.

#6 – Variation in the moon’s brightness. The top half will be closer to the center of the umbra and appear darker than the bottom. How obvious will this be?

#7 – Bring home a souvenir with your camera. If you have a telescope, you can hold a cellphone over the eyepiece to get great shots of the bright phases. During total eclipse, longer exposures of 1 to 10 seconds are necessary. For that you’ll need a tripod and a camera that can shoot time exposures. Telephoto lenses will pump up the moon’s size, but even a standard lens can do a great job of recording the sunset-colored moon in a landscape setting. Set your lens to its widest-open setting (f/2.8, 3.5) and expose 10-30 seconds to include the scene.

 

Don’t miss tonight’s rare triple Jupiter moon transit

All eyes will be on Jupiter tonight during the triple shadow transit. The map shows the sky facing east from the Chicago, Ill. region around midnight. Created with Stellarium

Jupiter and his four bright moons are one of the first things a beginning amateur astronomer looks at through a telescope. Watching the moons make new and surprising arrangements as they circle about the planet night after night makes for never ending observing enjoyment.

Jupiter’s moon Europa (at left) casts an inky dot on Jupiter on Sept. 24, 2013. Credit: John Chumack

Sometimes Jupiter’s shadow eclipses a moon, other times a moon passes in front of the planet and casts an inky black shadow on its cloud tops. Moons also orbit in front of Jupiter, though these events are more difficult to see unless you happen to catch the satellite right at the planet’s edge.

Tonight three of those moons – Io, Europa and Callisto – simultaneously cast their shadows on Jupiter’s cloud tops for just over an hour between 11:32 a.m. and 12:37 a.m. CDT (4:32-5:37 UT). This rare event last happened on March 28, 2004. They’re called shadow transits and single ones are fairly common. You can find online tables listing transits and satellite eclipses or use a free program like Meridian that gives you a little picture along with time information.

The March 28, 2004 triple transit. Shadows from left: Ganymede, Io and Callisto. You can also see the disks of Io (white dot) and Ganymede (blue dot) in this photo taken in infrared light by the Hubble Space Telescope. Credit: NASA/ESA

Seeing two shadows cross the planet at once is very uncommon, but three’s as rare as a blue rose. When averaged out, they happen only once or twice a decade. That’s why you should go out tonight with your telescope for a look.

If bad weather intervenes, the next transits won’t happen until June 3, 2014 (not visible in the Americas) and Jan. 24, 2015. After those we cool our heels until 2032.

Here’s the breakdown. The triple transit will be visible across the eastern half of the U.S., Europe and western Africa. East Coasters will have the best view in the U.S. with Jupiter some 20-25 degrees high in the northeastern sky around 1 a.m. local time. Things get more challenging in the Midwest where Jupiter climbs to only 5-10 degrees. By the time the planet rises in the mountain states, only Io and Europa’s shadows remain. If you live in the Pacific Time Zone and farther west, you’ll have to wait until 2015.

Jupiter polka-dotted with shadows cast by its moons Io, Europa and Callisto around midnight CDT Oct. 12. Watch for the Great Red Spot to come into view during the transit. Created with Claude Duplessis’ Meridian software

Let’s look at how each piece of the event will play out. Times below are CDT:

* Callisto’s shadow enters the disk – 10:12 p.m. Oct. 11
* Europa – 10:24 p.m.
* Io – 11:32 a.m.
** TRIPLE TRANSIT from 11:32 – 12:37 a.m.
* Callisto departs – 12:37 a.m.
* Europa departs – 1:01 a.m.
* Io departs – 1:44 a.m.

European amateurs have the best view with Jupiter high in the southern sky before dawn. In the eastern U.S., Jupiter’s up some 20-25 degrees in the eastern sky around mid-transit time. That should be high enough to escape the worst of the low-lying atmospheric turbulence that tends to blur planet images when using higher magnifications. The Midwest will see a Jupiter only 5-10 degrees high. Let’s hope the air is calm and clear!

Curiosity snaps sharpest-ever photos of “ring of fire” eclipse on Mars

Phobos, the larger of the two Martian moons at 17 miles across (27 km), creates an annular or ring eclipse as seen through the telephoto eye of the Mars Curiosity rover on Aug. 17. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

Now that’s what I call crisp! NASA just released a series of high resolution pictures of Phobos transiting the sun on August 17. Taken with the 100mm telephoto lens mounted on Curiosity’s mast, they’re the sharpest ever of an eclipse from another world.

Curiosity paused during its drive toward Mt. Sharp and aimed its mast camera straight at the sun to make the sequence of views three seconds apart. Because the sun was nearly directly overhead at the time, Phobos was at its closest and biggest, covering the maximum amount of the sun’s disk as possible.

Sequence showing the sun before, during and immediately after an annular or “ring of fire” eclipse. This eclipse occurred on May 10, 1994 over central Illinois. Credit: Bob King

When one object passes in front of another but only blocks a small portion of it, astronomers call it a transit, but Phobos is big enough and its passage so central, this event is better described as an annular or ring eclipse. We have ring eclipses on Earth too, but because the moon is nearly spherical and much larger than Phobos, it leaves a much narrower “ring of fire”.

Two additional photos from the Phobos eclipse sequence showing the moon entering (left) and exiting the sun. Credit: NASA

Astronomers will measure the moon’s position as it moved across the sun to more precisely calculate Phobos’ orbit. As described in a recent blog, Phobos is gradually moving closer to Mars and will one day be broken to pieces. If you care to browse additional and original pix of the eclipse, check out this Curiosity raw image page and scroll down to the Mast Cam section.

Curiosity sees unearthly moondance in Martian skies


Mars’ moon Deimos is occulted by Phobos on Aug. 1 as seen by Curiosity

What fun to live on a planet with TWO moons. Imagine stepping out into the Martian night to watch the moons Phobos and Deimos chase each other across the sky. NASA’s Curiosity rover did just that on Aug. 1 when mission control pointed its mast camera at the pair of tiny moons and snapped 41 photos as the larger and closer Phobos passed directly in front of little Deimos. In real time the “eclipse” took 55 seconds; the movie compresses that to 11. Even on Mars it was a marvelous night for a moondance.

With only one moon here on Earth, we miss out on the pleasures of dual moon gazing. The only thing that might come close is watching a cargo ship like the recent HTV-4 catch up and dock with the International Space Station.

Phobos orbits closer to Mars than Deimos and therefore completes a revolution around the planet more quickly, regularly overtaking its brother. The photos are the very first ever taken from Mars of an eclipse of one moon by the other.

Comparison showing how big the moons of Mars appear to be, as seen from its surface, in relation to the size that our moon appears to be seen from the Earth’s surface. Credit: NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ.

A 100mm telephoto lens was used to make the images which clearly show some of the larger craters on Phobos.

Both moons are tiny compared to our own. Deimos’ diameter is 7.5 miles (12 km) and Phobos 14 miles (22 km). It takes me longer to drive to work than cross the length of Deimos.

Even though Phobos is only about twice the size of Deimos, it appears much larger from the surface because it orbits much closer to the Red Planet – 3,700 miles (6,000 km) vs.12,400 miles (20,000 km).

Orbiting above the Martian equator and so close to the surface, Phobos can’t be seen from Mars’ polar regions. Its great speed also means it overtakes the planet’s rotation rate, rising in the west and setting in the east during the Martian night. Here on Earth, the moon moves in the same west to east direction but much more slowly, so that the faster-rotating Earth shuttles it from east to west during the night.

Phobos and Deimos up close as photographed by spacecraft. NASA scientists are studying the recent Curiosity images to determine precise orbits for the two moons as well as to gain a better understanding of the interior of Mars. Credit: NASA

Phobos’ tight orbit will ultimately lead to its demise. Its gravity induces tidal bulges in the crust of Mars which lag behind the fast-orbiting moon, causing it to gradually slow down and drop closer to the planet’s surface. In 50-100 million years Phobos will spiral in close enough for Mars’ gravity to break it to pieces. Deimos alone will remain to dimly light the Martian night.

In darkness the moon is reborn

If we could see the moon today, it would be a very thin crescent only a few degrees from the sun. Tomorrow it’s in new moon phase. Maps created with Stellarium

What’s old today but instantly becomes young again tomorrow? If you guessed the moon, you’re right! Today the moon winds up its current cycle of phases as an exceedingly thin crescent so close to the sun it’s invisible in the solar glare.

The moon’s cycle has always been a metaphor for life. Every month it’s born again as a thin crescent in the western evening sky, grows to a half-pie seven days later and reaches its full power and radiance when full at 14 days. After full, the moon’s radiance declines as its phase wanes to last quarter (21 days) and then to a whiskery crescent at dawn. Before it finally disappears in the sun’s glare, the moon, now 28 days old, reaches the end of its “life” cycle. But only briefly. The very next day, moments after new moon phase, it’s reborn again as an evening crescent.

When we run into troubles in our lives, we might look to the ever-renewing moon for inspiration.

The sky looking west-southwest a half hour after sunset Monday evening Feb. 11, 2013. You might be able to spot dimmer Mars in binoculars.

Tomorrow morning at 2:20 a.m. (CST) the moon will be exactly lined up with the sun and pass through new moon phase. Skywatchers in the western hemisphere won’t see the moon either day because it’s in the same direction as the sun and swamped by glare.

By Monday Feb. 11 however, the moon’s orbital motion will remove it far enough from the sun to be visible during evening twilight.  And there’s a bonus. The crescent will float a few degrees above the planet Mercury.

I’ve removed the atmosphere in this illustration so you can see where the moon is today at noon (CST), tomorrow morning when it reaches new moon phase and tomorrow Feb. 10 at noon. It passes north of the sun, which is in the constellation Capricornus. Notice all the planets in the neighborhood.

If we were to follow the moon today through new moon and into tomorrow, we’d notice it passes well north of the sun. Most of the time, the new moon is either north or south of the sun because its orbit is tipped about 5 degrees relative to Earth’s orbit.

The moon’s tilted orbit causes it to swing north or south (pictured here) of the sun from Earth’s perspective. A couple times a year however it crosses directly in front and a total solar eclipse is visible from somewhere on Earth. Illustration: Bob King

Over the course of its monthly cycle, it bobs up and then down along its tilted orbit. But 2 or 3 times a year, when the moon intersects the plane of Earth’s orbit at the same time as new moon phase, it crosses directly in front of the sun and we see a total solar eclipse. In fact, this is the only time we can see a new moon with the naked eye. It looks exactly like what you’d expect – a blank, black disk scrubbed free of its past life, waiting to begin the next as a tender crescent.

The new moon – black disk – is plainly visible silhouetting the sun during a total solar eclipse. Credit: Luc Viatour