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.
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.
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
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!
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.
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 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.
Now on to 2014 and a brand new host of celestial offerings. For the record, the majority of events listed are western hemisphere-centric and visible with the naked eye or binoculars. Times and dates are Central Standard or Central Daylight as noted. Clear skies!
1 – The very first day of the year offers the opportunity for North American observers to break their personal “youngest crescent moon” record. The moon will be just 12 hours old from the Midwest and 14 hour from the West Coast.
Watch for meteors from the Quadrantid shower before dawn on Jan. 3. Credit: John Chumack
3 – The peak of the annual Quadrantid meteor shower with a sharp maximum occurring at 1:30 p.m. (CST) on 1/3. Best time for viewing from North America will be 5-6:30 a.m. Jan. 3. The evening crescent moon will not interfere; eastern hemisphere skywatchers will have a dark sky at peak.
5 – Jupiter at opposition to the sun in Gemini and closest and brightest for the year. The planet rises at sunset and stays up all night. Great time for telescope viewing!
11 – Venus passes between the Earth and sun at inferior conjunction. For a week on either side of this date, you can see the planet as an exceedingly thin crescent in the daytime sky.
14 – Venus reappears very low in the eastern dawn sky 30 minutes before sunrise about this time
31 – Mercury at greatest elongation east of the sun and well-placed for viewing during evening twilight. Joined by a very thin crescent moon this day.
14 – Give that special someone a big kiss under tonight’s Valentine’s Day full moon
26 – Spectacular close conjunction of the crescent moon and Venus at dawn as seen from Europe and Africa. The two will be separated by only 0.3 degrees.
10 – The waxing gibbous moon occults the 3.6 magnitude star Lambda Geminorum for North America this evening.
Demonstration and path of the Erigone occultation of Regulus
20 – Asteroid 167 Erigone occults the bright star Regulus for observers living in a 45-mile-wide (72 km) band from New York City into Ontario, Canada. For those in the center of the path, Regulus will blank out for 12 seconds. The whole event will be easily visible with the naked eye. More information HERE.
20 – Spring (vernal equinox) begins in the northern hemisphere at 11:57 a.m. (CST)
Ganymede and Io will cast their shadows on Jupiter’s cloud tops for North and South American skywatchers on March 23. Credit: Created with Claude Duplessis Meridian software
21 – Saturn and the waning gibbous moon in close conjunction only 0.3 degrees apart as seen from Europe and Africa. Western hemisphere observers will see them about 3 degrees apart.
22 – Venus reaches greatest elongation of 47 degrees west of the sun in the morning sky. Despite its great separation from the sun, the planet will stand only about 15 degrees high at sunrise from mid-northern latitudes.
23 – Double shadow transit of Jupiter’s moons Io and Ganymede occurs from about 9:10-35 p.m. CDT. Easy to see in a small telescope.
8 – Mars at opposition and closest to the Earth since 2008. March-April will be the best time to observe the planet, when it’s up all night in the constellation Virgo near the bright star Spica and shining at magnitude -1.5, nearly as bright as Sirius.
The first of two total lunar eclipse in 2014 happens overnight April 15-16. Credit: NASA
15 – Total eclipse of the moon! The moon slips into Earth’s inner shadow starting at 12:58 a.m. CDT with maximum eclipse at 2:46 a.m. More information HERE.
15 – Asteroid Vesta at opposition and brightest for the year at magnitude 5.5. It should be easily visible with the naked eye from a dark sky site.
22 – Peak of the annual Lyrid meteor shower this morning with rates of 10-20 meteors per hour. Look to the south in wee hours before dawn. Some interference from the last quarter moon.
29 – Annular solar eclipse visible from Australia, the Southern Indian Ocean and Antarctica. More information HERE.
6 – Early morning peak of the annual Eta Aquarid meteor shower with rates of around 30 per hour. Each flash represents the burn-up of a small crumb left by Halley’s Comet.
10 – Saturn at opposition and brightest and closest for the year shining at magnitude 0. The rings will be inclined some 22 degrees to our line of sight, almost wide open. The planet will appear noticeably “out of round” in binoculars and present a beautiful sight in any size telescope.
24 - Possible big-time meteor shower from comet 209P/LINEAR when Earth passes through dust trails it deposited a century ago. Expect a peak between 2-3 a.m. (CST) with rates of 100+ per hour possible. No interference from the morning crescent moon.
25 – Mercury at greatest elongation east of the sun and easily visible low in the northwestern sky during evening twilight for observers in mid-northern latitudes.
3 – Triple shadow transit of Jupiter’s moons Callisto, Europa and Ganymede from 18:05 – 19:44 Greenwich time. Eastern Europe is favored. Not visible from the U.S.
21 – Start of summer (summer solstice) in the northern hemisphere at 12:51 a.m. CDT
Venus and the thin crescent at dawn on June 24. Stellarium
21 and for several days around this time – The International Space Station remains in sunlight throughout its orbit for northern hemisphere observers allowing us to see it on multiple passes throughout the night.
24 – Close conjunction of the crescent moon and Venus at dawn. With the moon so close you can use it to spot the planet even after sunrise.
5 – First quarter moon and Mars in conjunction less than a degree apart at dusk.
5 – Asteroids Ceres and Vesta – targets of NASA’s Dawn Mission – are less than 1/5 degree apart in Virgo during early evening hours. A rare event!
12 – The first of three “Super Moons” of 2014. The moon reaches perigee, closest to Earth, only 21 hours before it’s full and will appear slightly larger than a typical full moon.
29 – Peak of the annual Delta Aquarid meteor shower with a maximum of 20 per hour after midnight.
10 – Biggest Full Moon of the year! The moon turns full at 1:09 p.m. CDT. Nine minutes earlier it will have arrived at its closest point to Earth in 2014 of 221,765 miles (356,896 km).
12-13 – Peak of the annual Perseid meteor shower with rates of around 60-80 per hour. Spoiled this year by a bright moon just two days past full.
Comet Oukaimeden may glow around 8th magnitude in late August 2014 when it rises with the winter stars before dawn. Stellarium
18 – Spectacular close conjunction of Jupiter and Venus in the morning sky. They’ll be just 1/4 degree apart as seen from Europe and slightly wider by the time the pair rises for North and South American observers.
23 – Beautiful grouping of the thin crescent moon, Jupiter and Venus in the morning sky
25 – Mars and Saturn just 3.4 degrees apart in conjunction in the evening sky
27 – Comet C/2013 Oukaimeden should be within reach of binoculars in the morning sky near Orion.
29 – Neptune at opposition and brightest for the year at magnitude 7.8 in Aquarius
5 – Venus passes just 0.7 degrees north of Leo’s brightest star Regulus this morning in the east before sunrise.
8 – The final Super Moon of 2014 occurs 22 hours after perigee
22 – First day of fall (autumnal equinox) begins at 9:29 p.m. CDT in the northern hemisphere
Diagram show the moon’s path through Earth inner umbral shadow during the Oct. 8 total lunar eclipse. Credit: NASA
7 – Uranus at opposition and brightest for the year at magnitude 5.7 in Pisces
8 – Total eclipse of the moon, the second visible from the U.S. this year. Partial eclipse begins at 4:15 a.m. CDT with totality occurring from 5:25 – 6:24 a.m. Only the East Coast will miss a small portion of this eclipse. More information HERE.
19 – Comet C/2013 A1 Siding Spring encounters Mars. It will pass close enough that the coma may envelop the planet with a potential meteor storm to boot. Mars will be 151 million miles from Earth at the time and located in the constellation Ophiuchus and visible low in the southwestern sky at dusk.
18 – Comet C/2012 K1 PANSTARRS should be nearing peak brightness of magnitude 5.5. Mid-northern latitude observers can watch for it low in the southern sky in Puppis before dawn.
22 – The annual Orionid meteor shower peaks this morning with up to 25 meteors per hour visible. With the moon a day before new, dark skies will rule.
Diagram showing the visibility of the Oct. 23 partial solar eclipse. Credit: NASA
23 – Partial solar eclipse visible across the U.S. and Canada during late afternoon hours. At maximum for the central U.S. about half the sun will be covered by the moon. Click HERE for more information.
1 – Mercury reaches greatest elongation west of the sun and shines brightly at magnitude -0.5 in the morning sky for skywatchers in mid-northern latitudes. Best morning appearance of the year.
17 – Peak of the annual Leonid meteor shower. This year is an off-year for the Leonids with only 10-15 meteors visible per hour. Glare from the thick waning crescent moon will interfere somewhat.
7 – Double shadow transit of Jupiter’s moons Europa and Io occurs from 10:18 – 10:27 p.m. CST. They shadows will be on exactly opposite sides of the planet.
14 – Peak of the annual Geminid meteor shower, one of the richest and most reliable meteor showers with rates topping 100 per hour. Expect maximum activity overnight Dec. 13-14. Some interference from the last quarter moon after midnight.
21 – Start of winter (winter solstice) at 5:03 p.m. CST
If you know of an important event that I may have missed, please drop me a line at firstname.lastname@example.org
Ornament hanging from a Christmas tree? Cassini peers up at Saturn’s south polar region from 44 degrees beneath the ring plane last July. The black, curved stripes are the shadows of the rings on the planet’s atmosphere. Credit: NASA/JPL
Merry Christmas everyone! It’s been a joy to share the sky with you the past year. Thank you for sharing your comments, observations and photos. I hope this day finds you with family, friends and maybe even the stars.
We’ll soon step into a brand new year filled with eclipses – two lunars and a partial solar – an extremely close conjunction of Jupiter and Venus, a Mars opposition and much more. In a couple days I’ll have a complete month-by-month list of upcoming astronomical highlights.
Seen from STEREO-B, Earth, Jupiter and Venus line up inside a 2-degree-wide circle in conjunction on Dec. 24. Jupiter and the Earth were especially close – just 0.4 degrees or slightly less than one full width apart. Credit: NASA
Did you know that today the Earth is in conjunction with Venus and Jupiter today? Too bad you have to floating in outer space to see it. NASA’s STEREO-B probe, which looks back toward Earth from the opposite side of the sun, photographed a very compact grouping of the three worlds on Christmas Eve.
The three planets early this Christmas morning as seen by STEREO-B. Credit: NASA
Today they’re still very close with Jupiter practically on top of Venus. Coincidentally, a similar near-overlap of the two planets (as seen from Earth) on June 17, 2 B.C. was one possibility for the famed Star of Bethlehem we explored in yesterday’s blog.
The three Magi depicted in the Hortus Deliciarum by Herrad of Landsberg in 1185 AD.
We’ll never know for sure what “star” the Magi saw when they set off from Babylon to Jerusalem seeking their newborn king, but that doesn’t stop us from wondering whether it might have had a natural cause. There are many possible explanations, a few of which we’ll explore here.
“For we have seen His star in the East (upon rising) and have come to worship him” reads the biblical account of the Three Wise Men. After meeting with King Herod, they rode south to Bethlehem:
“… and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. When they saw the star, they were overjoyed.”
Precious little more was written about the star. If the Three Kings’ account had only mentioned a constellation or nearby star for reference, we could have narrowed down the possibilities. We do know the Magi’s general direction of travel and the accepted time frame of Christ’s birth between the years 7 and 2 B.C.
Bethlehem is 5.5 miles south of Jerusalem, where the Three Kings met with King Herod sometime around his death in 4 B.C.
We also know that whatever they saw moved from east to south. First visible in the east, the “star” next appeared over Bethlehem, located 5.5 miles (9 km) south of Jerusalem. As the Magi rode from Jerusalem they would have seen the apparition in the southern sky. Let’s now explore the possibilities:
* Meteors I think we can rule out meteors or their brilliant cousins, fireballs, because they’re too brief a phenomenon, and the Kings saw the apparition on at least two occasions. Meteors also don’t “rise” but streak across the sky from any direction.
Woodcut showing destructive influence of a fourth century comet from Stanilaus Lubienietski’s Theatrum Cometicum (Amsterdam, 1668). Comets in the past were often described as “hanging” over a location much like the ”star” of Bethlehem, but were typically seen as augurs of doom.
Halley’s Comet would have been a bright naked eye sight in Gemini in the east before dawn in late August 12 B.C. and again in the northwestern evening sky in September. A tempting possibility but the time frame is wrong – too early for Christ’s birth.
But another comet recorded in the Book of Hanwas observed within the correct time frame by Chinese astronomers in 5 B.C.:
“Second year of the Chien-p’ing reign period, second month (5 B.C., March 9-April 6), a suibsing (tailed comet) appeared at Ch’ien-niu for over 70 days.”
The comet first appeared in the constellation Capricornus, which would have been visible in the eastern sky before dawn from the Middle East in early spring. Assuming it came into view just after perihelion (closest approach to the sun), it would have traveled to the west and into the southern sky roughly within the time frame required for the Wise Men to travel from the Babylon to Jerusalem and finally to Bethlehem.
Or the comet could have been seen in the east before perihelion and then crossed over into the west-southwestern evening sky as a brilliant post-perihelion sight. The Bible also mentions “shepherds abiding in the field, keeping watch over their flock by night” at the time of the birth. This points to spring as being the likely season, the same as the comet’s period of visibility.
This almost sounds like an open and shut case except for a niggling detail. Comets were generally seen in ancient cultures as omens of doom and gloom, not bringers of good news like the birth of a new king. Comets scared people because they came out of nowhere and crossed the sky in unpredictable ways. To this day a bright comet’s appearance still stirs fears of impending catastrophe in some.
* Nova or supernova
A bright nova (temporary brightening of a white dwarf in a binary star system as it “feeds” on gas from its companion) or supernova would attract the attention of many. Most remain bright for weeks or months. Credit: creekandcave.com
Exploding stars are great candidates because they fit the description of a star, and in the case of a supernova, can appear as brilliant as Jupiter or Venus. That would certainly get the attention of the oriental astrologers, who kept a vigilant eye on the heavens waiting for the ancient prophecy of a “star” in Israel to be fulfilled.
Because of Earth’s revolution around the sun it’s even possible for a “new star” to appear first in one direction and then be visible a couple months later in another, especially if you factor in time of night. Unfortunately there are no records of novas or supernovas by the super-observant Chinese or anyone else occurring during the time frame.
* Conjunctions of bright planets
The western sky at the end of evening twilight on Feb. 25, 6 B.C. would have displayed a striking gathering of the planets Jupiter, Mars and Saturn. All three were within 7 degrees of each other. Created with Chris Marriott’s SkyMap software
Conjunctions occur when two or more bright celestial objects line up closely in the sky. A conjunction of two planets is not that unusual, but a gathering of three is and may have held great symbolic value in ancient times. One such triple conjunction involving Mars, Jupiter and Saturn took place in at dusk in the constellation Pisces on February 25, 6 B.C. Could this have inspired the Magi to begin their westward journey?
On Feb. 20, five days before the symmetrical gathering of planets , a very young evening crescent moon passed through the group. Created with Chris Marriott’s SkyMap software
Five days earlier the three were nearly as close and joined by a young crescent moon, an even more auspicious sight.
Of course there are problems with this scenario. The planets appeared in the western sky and the arrangement and number of planets visible would have changed months later when the kings rode to Bethlehem.
An amazing three conjunctions of Jupiter and Saturn from late May to early December 7 B.C. Created with Chris Marriott’s SkyMap software
A recurring conjunction of Jupiter and Saturn played out between May and December in 7 B.C. when the two planets were separated by just one degree (two full moon diameters) on three occasions in the constellation Pisces. The first close pass took place in the eastern morning sky on May 29; the second on Sept. 30 (southern evening sky) and the final pairing on Dec. 5, also in the southern evening sky.
A bright planet duo over so many months rates as an eye-catcher and the directions fit the bill, but the Magi described the object as a brilliant star, not a pair of stars. Even though a degree is a relatively small distance, it would have been easy to see them as two separate objects.
Venus and Jupiter just 0.6 arc minute apart – merged into one – on June 17, 2 B.C. Created with Chris Marriott’s SkyMap software
That brings us to the dual conjunctions of the two brightest planets of all – Jupiter and Venus – in the eastern sky at dawn from the Middle East on August 12, 3 B.C. and again 10 months later on Jun 17, 2 B.C. On both occasions astrologers would have watched the two planets come so close together they would have briefly merged into one before separating again.
OK, a keen eye might have separated the pair on August 12 when they were 2/5 of a moon diameter (12 arc minutes) apart, but they would have been far too tight on June 17 – just 0.6 arc minutes – for anything but a good pair of binoculars or telescope to split them.
During the first conjunction, the Magi would have seen this brilliant pairing in the eastern sky; on June 17 the following year, they lit up the western sky.
Despite appearing as a solitary brilliant “star”, this conjunction would not have been seen in the southern sky on a journey to Bethlehem but in the west, unless we interpret the direction implied in the Bible passage more broadly.
So what’s your pleasure? My best guesses for the Bethlehem Star are the Chinese comet of 4 B.C. or the pair of Jupiter-Venus conjunctions in 3 and 2 B.C. Or it could have been a succession of events – multiple conjunctions and a comet – that led the Magi to conclude that the prophecy of Christ’s birth would soon be fulfilled.
There’s another possibility – the supernatural. But that takes us outside the realm of science. Either way, the star remains a mystery, since we’ll never know for sure what caught the eye of the Three Wise Men as they scanned the heavens looking for signs of what would come.