Venus hides a star for 7 minutes

Venus occults or covers the star Lambda Aquarii April 17, 2014 

A planet covering a naked eye star is rarer by far than a total eclipse of the moon, and yet Venus did just that yesterday afternoon (U.S. time) from Australia, New Zealand and Micronesia. No one in the northern hemisphere witnessed the event; Venus passed south of the star from our perspective.

Jonathan Bradshaw of Australia captured this exceptional alignment well in his video despite the shaky atmosphere. Lambda Aquarii, a 4th magnitude star in Aquarius, was wiped from the sky for all of seven minutes.

It’s believed that the last bright star Venus or any major planet covered up was 2nd magnitude Nunki in Sagittarius for observers in eastern Africa in November 1981. Venus next occults Pi Sagittarii in 2035 and bright Regulus on Oct. 1, 2044. Mercury will cover up Theta Ophiuchi on Dec. 4, 2015.

Mars will pass in front of Jupiter in an extremely rare planet-over-planet occultation on Dec. 2, 2223. Stellarium

Very rarely, planets pass in front of each other. Over the 300 year span from 1800 to 2100 only 7 “mutual occultations” of this sort have or will occur. Venus crossed in front of Jupiter in 1818 – that was the last observable one. The next will happen when Mars passes in front of Jupiter on Dec. 2, 2223. Clearly, you and I and even our kids won’t be around for that event, but maybe some of our kids’ kids will.

Nature shows that once again even the most unlikely things can happen as long as one key ingredient is available – oodles of time.

See the space station this week / Jupiter and moon a sparkling sight tonight

One of the Expedition 39 crew members aboard the International Space Station photographed a curtain of aurora hovering over blue twilight over northeastern Kazakhstan recently. Click to enlarge. Credit: NASA

The International Space Station (ISS) returns this week to highlight the evening sky. Outside of Venus and the moon, the ISS is the brightest, star-like object in the nighttime sky. It orbits from west to east, the same direction the Earth rotates, and crosses the sky in about five minutes. At an altitude of about 250 miles, the station orbits above most of the auroras we see which is why astronauts get such cool photos of the northern and southern lights from orbit.

Expedition 38 photo of the Kavir Desert in Iran taken with a 200mm lens looks more like swirly water than rock formations. The lack of soil and vegetation allows the geological structure of the rocks to stand out. According to geologists, the patterns result from the gentle folding of numerous, thin, light and dark layers of rock. Later erosion by wind and water cut a flat surface across the folds exposing their internal structure. Click to enlarge. Credit: NASA

The new evening observing season begins for many locations across the northern hemisphere with passes happening once or twice a night. To watch the space station, go out a couple minutes before it’s expected to appear and look for a pale yellow “star” brighter than any other moving from west to east across the sky.

You might be able to also see the Progress 54 cargo craft in the coming week after it undocks with the ISS tomorrow morning and before its destructive re-entry over the Pacific Ocean on April 18. I’ll have viewing tips and times when they’re available. The departure makes way for the arrival of Progress 55 on April 9, which will deliver almost 3 tons of food, fuel and supplies.

Flight Engineer Oleg Artemyev looks at the Earth through the windows of the International Space Station’s cupola this past week. The Expedition 39 crew has been busy with biomedical research this past week focusing on how the immune system responds to living in space. Click to learn more. Credit: NASA-TV

Click HERE or HERE to find times and directions to look for your town. I’ve included a list of times when the ISS will be visible for skywatchers in the Duluth, Minn. U.S. region at the end of this article.

The half moon will be in conjunction with the brilliant planet Jupiter this evening. The map shows the sky facing southwest around 9 p.m. local time. Stellarium

While you’re waiting for the six-man crew of the station to fly over your house or apartment, don’t forget to look up at the first quarter moon in the constellation Gemini tonight. Just “three fingers” or 5 degrees above it shines Jupiter. They’ll make an eye-catching pair for sure.

The moon tonight as seen from North America. How many dark seas or lunar maria (MAH-ree-uh) can you see? Credit: Christian Legrande, Patrick Chevalley / Virtual Moon Atlas

For another easy observing project, try spotting all five of the lunar “seas” visible tonight. These largish, dark spots that form the face of the man in the moon are plains of now-solidified basaltic lavas that erupted 3-3.5 billion years ago in the basins of what were then enormous impact craters. They’re rich in iron and slightly younger than the lighter, older lunar highlands (white regions) which makes them appear darker.

Funny, isn’t it, that all that lunar tranquillity and sweetness should be marred by “crisis”, but I guess this half of the moon serves as a metaphor for life.

Space station viewing times for Duluth, Minn. region:

* Tonight Sun. April 6 starting at 8:29 p.m. Low pass across the south-southeastern sky. Max. elevation: 18 degrees (10 degrees equal one fist held at arm’s length against the sky)
* Mon. April 7 at 9:15 p.m. high across the southern sky. Brilliant pass with max. elevation of 66 degrees
* Tues. April 8 at 8:26 p.m. (high in the south at 42 degrees) and again at 10:03 p.m. across the northwestern sky. Max. elevation: 48 degrees.
* Weds. April 9 at 9:14 p.m. high in the northern sky. Max. elevation: 63 degrees

Mickey Mouse meets Jupiter

Amateur astronomers have been keeping watch over the “Mickey Mouse” ovals this observing season. The ovals are smaller-scale storms – the ‘nose’ rotates clockwise similar to a low pressure system in our planet’s southern hemisphere; the ears are high pressure center rotating counterclockwise. South is up. Credit: Damian Peach

This observing season, three of Jupiter’s many storms – called white ovals – happen to resemble the face of the famous Disney character Mickey Mouse. Two ears and a big nose. Just like Mickey, they might be up to mischief.

Jupiter has lots of these white ovals and brown ones, too. They’re hurricane-like storms in the planet’s atmosphere similar to but smaller than the behemoth Great Red Spot. Most don’t have names unless they’re around a long time or expand and merge with other ovals.

Like four little piggies in a row, four nameless white ovals appear near the Great Red Spot in this photo taken Dec. 29, 2013. South is up. Credit: Damian Peach

The white variety are swirling vortices of cold ammonia ice clouds high in the upper atmosphere. Astronomers find them at many locations tucked within the planet’s cloud belts. Brown ovals are holes in Jupiter’s cloud deck that let us peer deeper into the warmer atmosphere below. They typically only appear within a few degrees of the 20 degree north latitude zone.

The Hubble Space Telescope recorded the merger of three separate ovals in the mid-1990s into Oval BA a.k.a. Red Spot Jr. Notice a similar Micky Mouse shape prior to the merger. Credit: NASA/ESA

Back in the late 1930s, a bright white band of clouds appeared along Jupiter’s 30 degree south latitude zone and eventually coalesced into three separate counterclockwise spinning ovals named FA, DE and BC.

Red Spot Jr. rides Jupiter’s South Temperate Belt on March 7, 2014. South is down. Credit: Christopher Go

In the late 1990s the trio gradually met up merged into a single larger oval named ‘BA’ about as wide as the Earth around 2000. Five years later it developed a reddish-orange color, inspiring amateur astronomers to nickname it Red Spot Jr. The feature, now more circular than oval, still cycles around the planet to this day. Its color, like that of the Great Red Spot, is believed to come from the mixing of sulfur, carbon and phosphorus compounds sucked up from the lower atmosphere.

Zones, belts and vortices on Jupiter. The two most prominent dark stripes are the North and South Equatorial Belts. You can also see the Great Red Spot and many small white ovals. This 14-frame animation spans 24 Jovian days, or about 10 Earth days. The passage of time is accelerated by a factor of 600,000. Credit: NASA

The Great Red Spot (GRS) is one of the biggest storms in the solar system with wind speeds up to 400 mph (650 km/hr). Currently about 1.5 Earths wide,  it’s persisted for several centuries. For all we know it too resulted from a long-ago merger.

Coincidentally, you can see it late tonight across the Americas. The Spot sits squarely on the planet’s centerline around 12:30 a.m. CDT March 29 (1:30 a.m. Eastern, 10:30 p.m. Pacific). If that’s too late, you can start looking about 1-1/2 hours before these times when it will be to the east of centerline. Click HERE to find the best times for viewing the storm from your city.

A large brown oval is known was imaged by Voyager 1 on 2 March 1979. It’s 6,200 miles (10,000 km) across. Amateur astronomers often refer to large brown ovals as “barges”. Click to enlarge. Credit: NASA

Jupiter’s all weather all the time. Ovals change shape, push each other around and even merge. While you might strain to see white ovals or even Red Jr. in the telescope, make no mistake, these are big storms by earthly standards. Mickey Mouse’s ears are about one-third the width of the GRS or approximately half as big as our planet. I wouldn’t want to get close to that hurricane!

Rare treat: Catch Callisto’s shadow on Jupiter’s cloud tops tonight

Callisto’s shadow will follow along Jupiter’s south-south temperate belt from 9:09 p.m. to 12:54 a.m. tonight Feb. 22-23, 2014. A smaller telescope magnifying around 60x or higher will show it. Credit: Meridian software

If you have a 4-inch or larger telescope, tonight you’ll have the opportunity to see a rare shadow transit of the Jupiter’s bright moon Callisto. All four of Jupiter’s easily visible Galilean satellites, so-called because they were first seen by Galileo in the early 1600s, routinely pass in front of the planet and cast shadows on Jupiter’s cloud tops.

Europa is the smallest of the four with a diameter of 3,122 miles and casts the smallest shadow. Io’s shadow is larger and easier to spot, while Ganymede and Callisto – the largest of the quartet – cast the biggest shadows.

Jupiter’s four bright moons and their orbits. Io orbits closest. Each casts a shadow into space, which, when intercepted by Jupiter, appears as a black dot on the planet’s clouds. Credit: Ethan Siegel

Because Io and Europa orbit closest to Jupiter they make more frequent transits across the planet. Ganymede, being further from Jupiter, lines up less often.

Currently we see about five shadow castings per month for Ganymede with only about two for more distant Callisto. When you consider that some Callisto transits occur during daylight hours when Jupiter is unobservable, you can see how infrequent they truly are.

The last time Callisto “dotted” Jupiter was Feb. 6 between 3 a.m. and sunrise. Given the early hour, I suspect very few skywatchers across the Americas witnessed that event. Tonight’s transit occurs during convenient viewing hours starting at 9:09 p.m. CST (7:09 p.m. Pacific, 10:09 p.m. Eastern) and wrapping up about 3 1/2 hours later at 12:54 a.m. CST Feb. 23.

Shadow transits, particularly of Callisto, are leisurely affairs. That’s because it’s the most distant of the four moons and orbits slowest. Io, the closest, puts on a show lasting a little more than half as long or about 2 hours 10 minutes.

Callisto’s next shadow transit occurs on March 12 between 4:11-8:03 p.m. CST. With sunset at around 7 p.m on that date, the transit ends only an hour after sunset in the central U.S. After that we’ll have to wait until April for the next one.

I hope you’re skies are clear tonight so you can check it out.

Icy, plumy Europa finds a friend in Lake Superior

A lead of open water on Lake Superior near Duluth last week froze shut the next day. Credit: Bob King

I’ve always thought that Lake Superior in winter bore a resemblance to Jupiter’s icy moon Europa. Ice piles up in mounds of “broken plates” when the wind pushes a loose floe into the ice anchored to the shore.

Artist’s concept of a plume of water vapor thought to be ejected off the frigid, icy surface of the Jovian moon Europa, located about 500 million miles (800 million km) from the sun. Credit: NASA/ESA/K. Retherford/SWRI

Sometimes enormous cracks or leads appear and then freeze solid, forming a network of interlocking puzzle pieces. On subzero mornings, cold air blowing over the warmer water condenses into smoky swirls of vapor that rise and twist about like tiny tornadoes.

Jupiter’s moon Europa, which at 1,900 miles in diameter is about 250 miles smaller than Earth’s moon, has a miles-thick crust of ice. Like Lake Superior, it’s cracked and frozen, and though no one’s seen any open leads, it’s clear that enormous ice rafts once bobbed about in liquid water there, cracked into smaller sheets and refroze in temperatures as low as -370 F (-223 C).

In this photo of Jupiter’s moon Europa (inset), we see rafts of ice resembling polar pack ice on Earth. Large sheets once moved about and broke apart in liquid water and then refroze into position. Credit: NASA

Beneath the cracked and frozen crust, scientists have long speculated on the possibility of an extraterrestrial ocean. Recent observations by the Hubble Space Telescope of water plumes bursting from Europa’s south polar region offer the first proof that liquid H2O really does exist beneath the moon’s icy husk.

This graphic shows the location of water vapor detected over Europa’s south pole in observations taken by NASA’s Hubble Space Telescope in December 2012.
Image Credit: NASA/ESA/L. Roth/SWRI/University of Cologne

While no one can definitively say that’s the cause, it’s the simplest explanation. When confirmed, the finding would make Europa only the second moon in the solar system outside of Saturn’s Enceladus to spout water vapor.

There are plans for missions to Europa like NASA’s Europa Clipper that would use radar to penetrate the frozen crust, but the plumes offer a tantalizing way to get inside the little moon even sooner, according to Lorenz Roth of the Southwest Research Institute, lead author of the paper on the new observations:

“Future investigations can directly investigate the chemical makeup of Europa’s potentially habitable environment without drilling through layers of ice. And that is tremendously exciting.”

Illustrated flyby of Europa’s plumes – artist’s impression

The story of how Europa’s water plumes were discovered is fascinating in its own right. Astronomers were using the Hubble to study the faint ultraviolet light from an aurora, powered by Jupiter’s intense magnetic field, near the moon’s south pole. Here on Earth, the aurora is powered by solar electrons excited nitrogen and oxygen to glow; on Europa, excited hydrogen and oxygen atoms (the “H” and “O” in H2O) and their telltale glows pointed to water as the source.

The bright white swath cutting across the surface of icy Jovian moon Europa is known as Agenor Linea. It’s about 620 miles (1000 km) long and 3 miles (5 km) wide with only a section is pictured here photographed by the Galileo spacecraft. Scientists suspect that lineae like this one might vent water from an interior ocean. Click to enlarge. Credit: PIRL (Univ. of Arizona), Planetary Geosciences Group (Brown Univ.), Galileo Project, NASA

It’s possible that long cracks in the moon’s surface called ‘lineae’ might be venting water into space much like the now-familiar “tiger stripes” on Enceladus. Curiously, the moon only vents when it’s farthest from Jupiter in its 3.5 day orbit, hinting that gravitational stress on Europa when it’s closest to Jupiter might act as a sealing agent.

The Europa and Enceladus plumes have remarkably similar abundances of water vapor. Because Europa has a roughly 12 times stronger gravitational pull than Enceladus, the -40 F (-40 C) vapor for the most part doesn’t escape into space as it does at Enceladus, but rather falls back onto the surface after reaching an altitude of 125 miles (201 km), according to the Hubble measurements.

Check out Europa from your front yard observatory tonight. Stellarium

If you’d like to see Europa with your own eyes point a pair of 10x binoculars or small telescope at Jupiter tonight. You’ll find it to the right or west of Jupiter neatly lined up in a row with its fellow moons Io, Ganymede and Callisto. Take a look and ponder the possibility of liquid water and its potential as an abode for life 500 million miles from where you stand.

Jupiter meets the moon / Two comets pass in the night / Space station at dusk

A 22-degree halo, formed by light refracting through the faces of hexagonal ice crystals in cirrostratus clouds, reaches almost to Jupiter (lower left) last night Feb. 8. Credit: Bob King

The moving moon keeps things interesting on a very human time scale, gliding about one outstretched fist to the east every night. Last night ice-crystally clouds made a beautiful lunar halo that nearly but not quite touched Jupiter.

The moon will lie about a bit more than a fist to Jupiter’s right tonight and below it tomorrow night. Stellarium

Tonight the moon will lie to the right of the brilliant planet, while on Monday the two will be in conjunction with the waxing gibbous moon floating just below. It’s fun to watch the moon’s travels across the sky. Because of its 5.1 degree tilted orbit, the moon follows a slightly different track through the zodiac constellations each month in a cycle lasting 18.6 years. Planets move, stars drift westward with the seasons – taken all together, the moon makes repeated visits in ever-different arrangements with the bright stars and planets it passes every month.

This wide view shows much of the sky facing south about 90 minutes before sunrise. In addition to the bright planets, two bright stars – Antares in Scorpius and Spica in Virgo – join the scene. Stellarium

Yesterday morning was clear and I went out to look at comets and planets. How convenient that the morning planets are arrayed across the southern sky, so that one might begin on one end with Mars and finish up with Venus.

Like a kid, I started with the eye-candy planet Saturn first, then jumped over to the Venusian crescent and finally hit Mars as the sky was turning blue. What a lineup – wonderful opportunities to meet our planetary neighbors as long as you’re dressed for the weather.

Comets C/2012 X1 LINEAR (top) and C/2013 R1 Lovejoy appear to be chasing each other in this photo taken with a wide field 4-inch telescope before dawn Feb. 8, 2014. They were about 2.5 degrees apart at the time. Credit: Damian Peach

Comets C/2013 R1 Lovejoy at magnitude 8 and C/2012 X1 LINEAR at 9 still shine brightly enough to show in 6-inch and larger telescopes. Both are in the constellation Ophiuchus and well-placed for observation in the eastern sky just before the start of dawn. On Feb. 6 they were in conjunction only 2 degrees apart – a rare event. Despite appearances, the two comets are unrelated and many millions of miles apart.

Although they’re slowly parting, both are still within 3 degrees of each other, making it fun to drop in on both of them with a telescope. UK astrophotographer Damian Peach captured a wonderful image of the pair on Feb. 8. For finder maps and more information on Lovejoy and XI LINEAR, click HERE.

From aboard the International Space Station, astronaut Rick Mastracchio tweeted this view of Sochi, Russia, the site of the XXII Winter Olympic Games. Credit: NASA

Out at dusk these February evenings? The International Space Station (ISS) is making passes at us just in time for Valentine’s Day. The Expedition 38 crew has been working on biomedical research and performing tests on miniature free-flying robots inside the station called Synchronized Position Hold, Engage, Reorient, Experimental Satellites or simply, SPHERES.

Bowling-ball-sized robot spheres in the space station help with routine monitoring, maintenance and data transfer. Credit: NASA

The volleyball-sized robots has been working on the station since 2006; they take photos and videos, make Wi-Fi connections and fly in formation. They’ll also be used outside the station to make repairs, conduct inspections and assist in de-orbiting malfunctioning spacecraft.

From the ground, the football-field sized space station looks like a brilliant yellow star traveling from west to east across the sky. I’ve listed a few times below when it’s visible from the Duluth, Minn. region. For times and directions for your town, go to Heavens Above or key in your zip code at Spaceweather’s Satellite Flybys link.

* Tonight Feb. 9 starting at 5:57 p.m. Low pass across the south-southeast. Max. brightness at magnitude -1.8. Second brief, brilliant appearance in the west at 7:33 p.m. Disappears into Earth’s shadow 2 minutes later. Magnitude -2.4

* Mon. Feb. 10 at 6:44 p.m. Fabulously bright, high pass across the top of the sky. Mag. -3.4!

* Tues. Feb. 11 at  5:56 p.m. high in the southern sky. Glides very close to Jupiter seconds before 6 p.m. Mag. -3.0

* Weds. Feb. 12 at 6:44 p.m. high in the northern sky. Mag. -2.7

Year’s wimpiest full moon still worth howling at

The nearly full moon and Jupiter shine over downtown Duluth, Minn. US last night. Details: 35mm lens at f/2.8, 1/4″ exposure ISO 800. Credit: Bob King

January’s Full Wolf Moon will blaze over your town from high overhead in the constellation Gemini the Twins tonight. Named for wolf packs that howled outside Indian villages during the cold (and often lean) winter months, the name feels appropriate. Few sounds like a solitary wolf howling on a subzero night give voice to the struggle to stay alive.

Moon on a stick! A beautiful corona formed around last night’s moon when high clouds blew by. Tiny droplets within the clouds diffract the moon’s white light into a bullseye of colored rings. Credit: Bob King

A fist to the moon’s right you’ll see the planet Jupiter, not as close as it was last night but still near enough to catch the eye.

Tonight’s moon is special in a rather odd way. It’s the farthest full moon of the year. Normally I’m writing to alert you about lunar perigee or the closest full moon of the year, better known these days as the “Super Moon”.

Instead, this evening’s moon turns full at 10:52 p.m. CST just 2 hours 59 minutes after reaching apogee or greatest distance from the Earth.

The moon’s distance from Earth varies because it revolves in an elliptical or oval-shaped orbit with the Earth slightly off to one side. Every lunar revolution features a monthly perigee and apogee. When those time coincide with full moon we have either Super Moons or, for lack of a better word, Wimpy Moons.

Perigee and apogee moons from April and October 2007. Credit: Tom Ruen

At apogee at 7:53 p.m. the moon will lie 252,610 miles (406,536 km) from the Earth – about 13,700 miles farther than average and 31,000 miles farther then when closest. That means tonight’s full moon will be about 1/6 or 16% smaller than the biggest Super Moon.

Will you see this with your eyes? Probably not unless you have a photographic memory able to compare the Wolf Moon to the Super Moon of June 23, 2013 six months ago.

The rising or setting moon is one Earth radius (red line) farther from an observer than when it’s high overhead. Illustration: Bob King

Want to see the smallest possible full moon tonight? Catch it at moonrise when it’s farthest from your location. How so?

When rising, the moon is 2% smaller than when overhead because we’re looking across the Earth’s radius (4000 miles) to see it. As the moon rises higher it also gets closer to the Earth, reaching minimum distance when it’s due south. That happens around midnight tonight.

After midnight it spends the rest of the early morning hours moving farther away until it’s again a full Earth radius distance further when perched on the western horizon at sunrise tomorrow. Sounds loony, but it’s true!

Jupiter co-stars with the moon in tonight’s sky

The nearly full moon joins Jupiter tonight. This map shows the sky facing east around 7 p.m. local time. The two will be just 4.8 degrees apart later this evening. Stellarium

The moon’s steady eastward progress puts it in Jupiter’s vicinity tonight. Always cool when the two brightest lights in the evening sky get together. They add extra sparkle and interest to a night’s walk.

Telescope users can watch the largest moon Ganymede exit the Jupiter’s shadow after eclipse. You’ll see the first glimmer of the moon very close to the east edge of the planet directly across from the North Equatorial Belt beginning around 9:20 p.m. CST (10:20 Easter, 7:20 Pacific).  Watch as it quickly swells to its usual brightness in just a few minutes.

Looking for aurora tonight? Check out the Winter Hexagon + 2

This map shows the sky facing southeast around 8:30 p.m. local time tonight. The splendid gathering of stars – the Winter Hexagon – is just now coming into good view during early evening hours. The entire figure is quite large, starting with Sirius low in the south and topping out with Capella near the zenith. Stellarium

Update 9 a.m. Jan. 10: The blast of particles from the solar flare in big sunspot group 1944 was much weaker than expected. Some of it slid by Earth yesterday afternoon but only fired up auroras in Arctic latitudes that were in darkness at the time. There’s still one more chance for auroras tonight as the remainder of blast passes by.

– 12:05 a.m. Jan. 10: Still nothing visible from Duluth though there’s been a generally upward trend in activity over the past few hours. You can check the extent of the auroral oval HERE. The red line indicates the southern limit of aurora visibility. Though more technical, a good indicator of an impending aurora is the real-time Bz graph from the ACE spacecraft. If the red squiggly line dips sharply southward – toward the bottom of the chart (lower than -10) – be alert for potential northern lights.

While you’re out facing north hoping the aurora paints your sky tonight take a look around your backside to the south. Starting around 8-8:30 p.m. local time the complete Winter Hexagon – a beautiful hexagonal array of the brightest stars of the winter – tilts upward in the southeastern sky.

Each star or stars, as in the case of Castor and Pollux, which both belong to Gemini the Twins, heads up a particular constellation:

* Capella in Auriga the Charioteer
* Aldeabaran / Taurus the Bull
* Rigel / Orion
* Sirius / Canis Major the Great Dog
* Procyon / Canis Minor the Little Dog

What about the “+2″. These odd stars out – Betelgeuse and the planet Jupiter – aren’t part of the Hexagon but just happen to be fenced in by it. Count them all up and you’ve got nine shimmering sky objects, eight of which are first magnitude or brighter (Castor is magnitude 1.9) and located in the same tract of sky. What an attention grabber.

The Winter Hexagon with Jupiter in Taurus in 2012-13 (upper right) along with some insidious light pollution (lower right). Credit: Bob King

You might be surprised to know that winter skies are often more light polluted than those of other seasons. Streetlights and other forms of lighting reflect off the snow cover and bounce straight up into the sky. The difference is striking from where I live – the wash of light from the city reaches half again as high in the southern sky as during the fall.

The Hexagon’s concentrated radiance plus additional bright stars in the region leave the impression that winter is the clearest, darkest time of year when it may very well not be.

Parts of the world that don’t receive snow in the winter are better off, and if your haze and humidity levels are lower than as well, the winter stars may indeed sparkle that much brightly.

So enjoy the Hexagon tonight, and may a fine display of northern lights make you turn around the other way.

Jupiter 2014 Opposition – Biggest, Brightest, Closest for the Year Tonight!

Jupiter rides high in the eastern sky smack in the middle of the constellation Gemini the Twins this month. The bright stars Castor and Pollux (left of the planet) add extra sparkle to the scene. Jupiter is at “opposition” or opposite the sun in the sky, rising when the sun sets and remaining visible the entire night. Credit: Bob King

Today the biggest planet of them all is at opposition to the sun and closest and brightest for the year. You’ve no doubt noticed Jupiter rising in the northeastern sky during late evening twilight –  its penetrating pale yellow light catches the eye before any other star in the sky. Outside of Venus, which will depart the evening sky in just one week, Jupiter is the brightest planet in the heavens.

Jupiter and Earth are lined up on the same side of the sun today. Seen from the ground, Jupiter rises around sunset opposite the sun. Illustration: Bob King

Once a year, Jupiter and Earth draw closest to one another as they line up on the same side of the sun. 391 million miles (629 million km) separate the two worlds, which may sound like a lot, but that’s a good deal closer than when they’re on opposite sides of the sun. Try 584 million miles (940 million km) this July 24 when the planet is in solar conjunction.

Being close also means being big and bright. Jupiter appears 47 arc seconds across (60 seconds = 1 arc minute = 1/30 the moon’s diameter) and beams at magnitude -2.7 or three times brighter than Sirius, the brightest star.

Jupiter’s four brightest moons – Io, Europa, Ganymede and Callisto – are visible in 7-10x binoculars as “stars” lined up very close to the planet. The key to seeing them is focusing sharply and holding the binoculars steady. Credit: Bob King

Even binoculars will make it look “fatter” than a star, plus you can see two or three and sometimes up to four bright moons. Known as the Galilean moons because they were first seen by Galileo, the satellites shuffle back and forth around the planet, changing positions from night to night. The closest-in moon Io takes only 1.8 days to circle Jupiter; the furthest of the four, Callisto, completes a revolution in 16.7 days.

Jupiter and moons this evening around 9 p.m. CST (add an hour for Eastern, subtract an hour for Mountain and 2 hours for Pacific). By chance, they’re lined according to distance with Io closest and Callisto farthest. Two dark cloud bands – the North and South Equatorial Belts – will also be visible in small telescopes. Stellarium

To find out what Jupiter’s satellites are doing any time of day or night, check out Sky and Telescope’s Jupiter Moons utility. It also lists  times when the moons pass in front of or are eclipsed by the planet.

Largest of the eight planets, Jupiter is completely covered by clouds of ammonia ice and has lots of weather just like Earth, making it one of the most rewarding objects to follow in a telescope.

Low magnification (40- 50x) will easily show two gray “tire tracks” across the planet’s disk. These are the North and South Equatorial Belts which flank Jupiter’s equator. Higher power, steady air and visual concentration will reveal thinner stripes like the North and South Temperate Belts.

Strong winds whip Jupiter’s clouds into alternating dark belts and bright zones. Sulfur and possibly phosphorus compounds may be responsible for the dark tone of the belts as well as the Great Red Spot. At Jupiter’s distance from the sun, ammonia exists as ice crystals. Credit: NASA/JPL

Dark belts are separated by lighter zones and the whole works is streamed into stripes by narrow, high-speed winds called jets that border the zones and belts. Winds rip along at up to 400 mph (640 km/hr). Because Jupiter makes a complete spin on its axis at the amazing rate of just 9.9 hours, you can watch new features rotate into view by revisiting the planet in your telescope several times during the night.

With Jupiter well placed for observing two hours after sunset until two hours before sunrise, it’s possible to observe the planet through more than one full rotation over the long winter night for northern hemisphere skywatchers.

Jupiter’s always changing! These two photos, taken by Australian amateur astronomer Anthony Wesley, show the dramatic fading of the South Equatorial Belt (SEB) several years back. It’s since returned. The red oval is the Great Red Spot, also subject to changes in color and size.

Jupiter’s weather is as changeable as Earth’s. Belts narrow, widen, split in two or even disappear altogether for a couple years before reforming. The familiar Great Red Spot (GRS), a hurricane-like storm more than twice Earth’s diameter that’s raged for centuries, changes color from pale tan to brick red. This year it’s redder than in the previous few years and somewhat easier to see. I say somewhat because the GRS has been shrinking over the years.

Amateur astronomers recognize two “sides” of Jupiter. The Red Spot side not only has the GRS but also lots of turbulent detail within the SEB. The other side has sometimes been called the “dull” side of the planet because it lacks a celebrity. Left photo by Damian Peach; right photo by Martin Mobberley

Drawings from the 1800s show it as a big red hot dog easily twice the size it is now. Small telescope users should use magnifications of at least 100x and plan their hunt when the air is least turbulent (steady seeing). The best time to view the GRS is when it’s lined up on the planet’s meridian and squarely faces Earth. To find out those times for your location, click HERE.

Despite the inevitable cold weather winter brings, January is the best time to go outside and enjoy a peek at Jupiter. For northern hemisphere observers, the planet is now at its highest point in the sky, far above haze and much of the turbulent air present at lower altitudes. If you’re using a telescope and taking it outdoors from inside your warm house, remember to let it cool down for at least a half-hour before you observe the planet otherwise heat from the tube and optics will distort and soften the image.

Have at it by Jove!