Weird auroras / Mercury meets a dainty moon / See 5 evening planets!

An oval patch of glowing green aurora appeared in the northern sky in Cassiopeia last night (April 17). Credit: Bob King

An oval patch of glowing green aurora pulses in Cassiopeia last night (April 17). Credit: Bob King

It’s been a fantastic 4 nights of northern lights. For now, Earth’s magnetic environment has returned to quiet conditions. Similar to the run of auroras that began on St. Patrick’s Day, this one finished with the same peculiar, sausage-shaped patches.

Last night I noticed a single elongated glow about two fists across in the northern sky in late twilight that slowly pulsed in brightness, often disappearing for 10-15 seconds and then reappearing in the same spot. Like breath on a mirror.

Another view of the diffuse aurora seen last night across the northern sky. Credit: Bob King

Another view of the diffuse aurora seen last night across the northern sky. Credit: Bob King

During the night, the patch slinked slowly westward into Cassiopeia and then disappeared altogether around 11 o’clock. At midnight it reappeared in the northeastern sky below the Northern Cross.  The strange apparition added quiet intrigue to the evening’s boisterous calls from the frogs.

Use bright Venus to help point you in the right direction. This map shows the sky facing west-northwest around 40 minutes after sunset. Created with Stellarium

Use bright Venus to help point you in the right direction. This map shows the sky facing west-northwest around 40 minutes after sunset. Mercury is 7° to the lower right of the moon. Created with Stellarium

Tomorrow night (April 19), look to the northwest about 40 minutes after sunset for a rare alignment of a day-old moon and two planets. One of them, Mars, has been around since last spring. Back then it was much closer to Earth and brilliant. Since then the two planets have separated with Mars now far away and rather faint. You wouldn’t ordinary seek it out so low in a bright sky, but the youthful crescent moon will certainly lure you there.

Mercury's approximate path and altitude during its dusk appearance this spring. Notice how its phase changes from the current gibbous to half to crescent. Source: Stellarium, Bob King

Mercury’s approximate path and altitude during its dusk appearance this spring. Notice how its phase changes from the current gibbous to half to crescent. Source: Stellarium, Bob King

The moon will be just a bit more than one day old and appear as a razor-thin sliver about 5-7° high (three to four fingers held at arm’s length). It should be easily visible from anywhere with a wide open view to the west-northwest. Because of its relative faintness, Mars will probably require binoculars to see. Focus on the moon first and then slide to the right to find the star-like planet.

As an inner planet, Mercury goes through phases just like Venus and the Moon. We see it morph from crescent to “full moon” as its angle to the Sun changes during its revolution of the Sun. Credit: ESO

As an inner planet, Mercury goes through phases just like Venus and the Moon. We see it vary from crescent to “full moon” as its angle to the Sun changes during its revolution of the Sun. Credit: ESO

Mercury shines at magnitude -0.5, even brighter than Vega or Arcturus, but it’s only a few degrees high, so you might need binoculars to see it, too. Once again, the moon comes to the rescue. Look either with your eyes or binos 7° (four fingers) to its lower right.

Mercury quickly moves up from the horizon in the next two weeks for its best evening appearance of the year for northern hemisphere skywatchers. As it comes into better view, the planet will slowly fade and change phase just like the moon. You can see the phases through a small telescope magnifying about 75x. Be sure to look for Mercury early when it’s highest or the blurring effect of the atmosphere will turn it into a ball of quivering mush.

Saturn pops up in the head of the Scorpion in late April around 11-11:30 p.m. This photo was taken early this morning just after midnight. Credit: Bob King

Saturn pops up in the head of the Scorpion in late April around 11-11:30 p.m. This photo was taken early this morning just after midnight. Credit: Bob King

With Mercury joining the scene, we now have five — count ‘em — five planets visible in the evening sky. Throw in the Earth and that makes six out of a total of eight! Mercury and Mars hang low in the west; Venus can’t be missed, shining like a lighthouse high in the west at dusk; Jupiter dominates the southern sky in Cancer and if you stay up till 11:30, you’ll see Saturn rise in Scorpius low in the southeastern sky.

Such riches for planetary enthusiasts. Go out and meet your solar system at the next opportunity.

Mercury returns, planets align, life is good

Mercury is just entering the picture tonight but by May 10 it will be easy to see, along with three other evening planets, 45 minutes after sunset in the northwestern sky. The pink arc is the ecliptic, the apparent path the sun takes during its yearly travels. It’s also followed closely by the planets and moon. Click to enlarge. Created with Stellarium

Planets are popping up everywhere. We’ve touched on Jupiter and Mars many times the past few months, but recently Saturn and now Mercury have entered the scene. Maybe you’ve noticed Saturn now in the southeastern sky at nightfall. From the northern U.S. and southern Canada, it’s bright but low at nightfall. Saturn reaches opposition a week from now when it will be at its closest and brightest for 2014. Each night that passes, the ringed rises higher and becomes better placed for viewing.

Mars, brilliant and fiery orange-red, now dominates the southern sky before midnight, standing above fainter Spica in the constellation Virgo. Only a month past opposition, we’re smack in the middle of the best time to observe the Red Planet through a telescope. I try to catch a look every clear or partly cloudy night but nearly missed the chance last night.

Two different hemispheres of Mars. The left image from May 2 shows a shrinking north polar cap and clouds blanketing the base of several volcanoes (dark dots) along the left edge of the planet. Right view taken on April 14 shows the hemisphere currently facing U.S. observers at nightfall. Credit: Christopher Go (left) and Anthony Wesley

The sky suddenly cleared after almost a week of overcast. I figured I’d walk my dog first and then set up the telescope, but 15 minutes later, clouds reappeared in the west. I turned around and footed it back home as quickly as I could, catching just five minutes of Mars light before a blanket of clouds suffocated the starry sky. Yeah, it was worth it.

Jupiter on May 2 displays its two most prominent belts visible in small telescopes, the North and South Equatorial Belts. Credit: Christopher Go

You might think it’s crazy to look at a planet night after night. Amateur astronomers do this for several reasons. First, most nights the air is too turbulent for a clear, sharp view. Looking often maximizes your chances of seeing the planet crisply in stable air. Almost nothing in observational astronomy beats viewing Mars or Jupiter or Saturn without air currents gooing things up. At these special times the dross falls away and the planet looks absolutely real. No exaggeration, you feel like you’re right there.

Planets also rotate. One hemisphere faces us one night, another on a different night or different time of night. Repeated observation gives you a certain familiarity with the “landscape” and alerts your eye to any changes happening. Remember, on most planets, weather plays a role in their appearance. Unexpected changes like a newly-spawned dust storm on Mars or the disappearance of a cloud belt on Jupiter lend an air of anticipation to the night’s viewing.

The sky from the central U.S. facing west-northwest this evening May 3 about 25 minutes after sunset. Mercury will be very low (about 3-4 degrees) but bright. The crescent moon passes just north of the star Eta in the constellation Gemini. Stellarium

Let’s talk about Mercury a minute. Skywatchers blessed with a clear view down to the west-northwest horizon can find the little planet as soon as this evening. Face the sunset direction about 20 minutes after sunset and sweep a few degrees above the horizon with your eyes or a pair of binoculars. The planet now shines at magnitude -1.4 or nearly as bright as it can, an equal to Sirius, the brightest star.

If you don’t succeed, try again in a week on the 10th. After the late January show, the period from May 10-23 will be the best time this year to see the planet at dusk.

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

Super-Earths with super-potential discovered circling star Gliese 667C

This artist’s impression shows the view from the extra-solar planet Gliese 667Cd looking toward the planet’s parent star Gliese 667C. Above center the more distant stars in this triple system (Gliese 667A and Gliese 667B) are visible and to the left in the sky, the newly discovered Gliese 667Ce can be seen as a crescent. A record three planets in this system lie within the star’s habitable zone.Credit: ESO/M. Kornmesser

Meet Gliese 667C, the little star with the big family. Gliese 667C resides near the “stinger” stars in the tail of Scorpius the Scorpion. You can even see it in binoculars on a clear night low in the southern sky. But it’s what you can’t see that makes this star so cool. It’s swarmed by at least six orbiting planets, three of them in the star’s habitable zone where liquid water might puddle on their surfaces.

This diagram shows the system of planets around the star Gliese 667C.  It’s the first found with a fully packed habitable zone. The relative approximate sizes of the planets and the parent star are shown to scale, but not their relative separations. Credit: ESO

Three of the six, Gliese 667 Cb, Gliese 667 Cc and Gliese 667 Cd, were found in the past year with Gliese 667Cc orbiting in the habitable zone. This week a team of astronomers using powerful telescopes in Chile and Hawaii announced the discovery of three more planets – Gliese 667 Cd, Ce, Cf – and possibly a fourth. All seven orbit closer to their host star than Mercury does to the sun. Heck, there are so many planets, they completely fill up all the orbital slots in the star’s habitable zone.

Another artist’s impression shows a sunset seen from the super-Earth Gliese 667 Cc. The brightest star in the sky is the red dwarf Gliese 667 C.The other two more distant stars, Gliese 667 A and B, appear in the sky also to the right. Astronomers have estimated that there are tens of billions of such rocky worlds orbiting faint red dwarf stars in the Milky Way alone. Credit: ESO

Three of them are super-Earths, planets more massive than our own but not quite as big as Uranus or Neptune. Because they circle a much cooler and less massive red dwarf star, they’re not lava-hot hells like so many other extra-solar planets but more temperate worlds where water could be stable. The Gliese system has the greatest number of super-Earths ever found in a star’s habitable zone to date.

You can use this map to help you find Gliese 667, located in the tail of the scorpion. The map shows the sky facing south around 11 p.m. from the northern U.S. The star will be higher up from the southern states. It shines at 6th magnitude and easy in binoculars. Stellarium

Gliese 667 lies just 22 light years from Earth and though it appears single in binoculars, it’s really a triple system. All the planets orbit the dimmest of the three dwarfs, Gliese C, which itself orbits in tandem with a tight pair of orange dwarf stars, Gliese A and B. A resident on any one of the new-found planets would look off toward the pair and see a bright double star shining day or night and providing about as much light as the full moon.

Water as always is key. Given their location, at least three of Gliese 667’s planets have the potential to support life.


3 bright planets slow jam at dusk this week

Jupiter, Venus and Mercury last night 35 minutes after sunset low in the northwestern sky. Details: 150mm lens at f/2.8, 1/30″, ISO 400. Photo: Bob King

Last night we finally cleared off after four solid days and nights of gray and rain. Sparkling low in the northwestern sky was a most welcome sight – Venus, Jupiter and Mercury. This week they will undergo to a series of remarkable gatherings in the early evening sky.

Venus leaped out immediately as the brightest of the trio. It stood 6 degrees above the horizon; that’s three fingers held horizontally at arm’s length. Jupiter jumped out next some 5 degrees to the upper left of Venus. Mercury, the dimmest of the the bunch, was very easy in binoculars but took a bit of concentration to see with the naked eye.

I’ve highlighted several nights of the triple planet gathering over the coming nights. Jupiter is colored yellow and Mercury pink to tell which is which. Created with Stellarium

This jam has just begun. Watch over the coming nights as the three planets move closer together to form a series of ever-changing jeweled triangles. Tomorrow night Mercury and Venus will be closest (1.4 degrees); Mercury and Jupiter on Memorial Day (2.3 degrees) and Venus and Jupiter on May 28 (1 degree).

All you need to see them is an unobstructed view to the west-northwest. You can begin your search about 30 minutes after sunset; get an early start because the planets set about an hour later. Binoculars can prove most helpful in case the sky’s hazy or if you have difficulty finding Mercury.

Left: If you could hover high above Earth’s north pole today and look down on the solar system, this is how the evening planets would be laid out. You can easily see how far they are from one another. At right, viewed from the flat plane of the solar system, they appear to bunch up. These occasional bunches caused by perspective are called conjunctions. Illustration: Bob King

As you can see from the nightly maps,  Mercury moves upward from the western horizon to join Venus, passes it and then teams up with Jupiter. Mercury moves rapidly because it orbits the sun most closely. Venus is also moving up from the west but more slowly, so it essentially stays in the same spot. Jupiter meanwhile drops down toward the western horizon. Earth’s motion around the sun is much faster than Jupiter’s causing the sun to literally “get in the way” between our two planets. From our perspective, Jupiter will soon disappear in the solar glare and won’t be seen again until early July when it reappears in the morning sky.

Although the trio may appear close to one another in the sky, they’re millions of miles from each other and the Earth. We see them together because they lie along the same line of sight for the coming week.

NASA’s Kepler spies 3 new “Goldilocks” planets

Relative sizes of the newly discovered habitable-zone planets and Earth. Left to right: Kepler-69c, Kepler-62e, Kepler-62f and Earth (except for Earth, these are artists’ renditions). Image credit: NASA Ames/JPL-Caltech

NASA’s Kepler Mission proves once again that Earth has relatives or at least good friends. The agency announced the discovery today of three new super-Earth-size planets around two different stars. All three are rocky planets orbiting within their host stars’ “Goldilocks Zone”, a region neither too hot nor too cold but just right for liquid water to exist on a planet’s surface.

The diagram compares the planets of the inner solar system to Kepler-62, a five-planet system about 1,200 light-years from Earth in the constellation Lyra. The three inner planets orbit so close to the host star, they’re too hot to be in the Goldilocks Zone. Credit: NASA Ames/JPL-Caltech

Two of the new planets – Kepler-62e and 62f – circle the star Kepler-62 along with three other planets for a total of five in the system; Kepler-69c, the third super-Earth, orbits Kepler-69 along with one additional planet. Kepler-62 is only 2/3 the size of the sun, 1/5 as bright and resides 1,200 light years away in the constellation Lyra the Harp. Kepler-62 is slightly smaller and less luminous than the sun and lies 2,700 light years from Earth in Cygnus the Swan.

The diagram compares the planets of the inner solar system to Kepler-69, a two-planet system about 2,700 light-years from Earth in the constellation Cygnus. The two planets of Kepler-69 orbit a star that belongs to the same class as our sun, called G-type. Credit: NASA Ames/JPL-Caltech

Here are the specs on the super-Earths, defined as planets with masses greater than Earth but less than that of the planets Uranus and Neptune which are about 15 times more massive than Earth:

* Kepler-69c — 70% larger than Earth, the smallest yet found in the habitable zone of a sun-like star. It circles its sun in 242 days with an orbit similar to that of Venus.

* Kepler-62e —  60% larger than Earth, orbits every 122 days in the the habitable zone’s inner edge.

* Kepler-62f — 40% larger than Earth, the smallest known habitable zone exoplanet, orbits every 267 days.

Although some 871 exoplanets have been discovered to date only 10 have been found in their host stars’ habitable zones. Since mission start on April 8, 2009, Kepler has detected 2,740 candidates of which 122 have been confirmed. Planets are becoming as common as rabbits it would seem.

Kepler watches for dips in a star’s brightness when a planet transits or crosses in front of it.

Kepler uses the transit method to spy its new planets, keeping a constant eye on more than 150,000 stars in Cygnus and Lyra just waiting for a planet to transit or pass in front of one of them. The resulting dip in the brightness of the star reveals the planet’s size relative to its host. Based on information we read in a star’s light using a spectrograph, we can estimate the star’s size and then calculate the planet’s size. Three successful transits are required to become a planet candidate. Earth-based telescopes then perform follow-up observations to confirm Kepler’s results.

The significance of today’s announcement is simple. With every new potentially habitable planet discovered, we learn more about how Earth fits in. How long will our blue globe remain unique as planet finding turns from trickle to torrent?

Click HERE for more details.

A painting in the western sky

Tonight's gathering of Moon, Jupiter, Venus and transcontinental airliner in the western sky in mid-twilight Sunday. Details: 35mm lens at f/4.5, ISO 400 and 6 seconds. Photo: Bob King

I hope you had a chance to see the spectacle of moon and planets in the western sky Sunday evening. The full circle of the moon is visible alongside Jupiter. The bright part of the circle (crescent) is illuminated by the sun, while the remainder of the moon shines by sunlight reflected from Earth’s clouds, water and land. Earthshine is much fainter than direct sunlight, which is why that portion of the moon glows only weakly.

Not far above the pair is Venus and the Seven Sisters star cluster. Very eye-catching all!

Tonight the moon will be next to Venus and even closer than it is to Jupiter tonight, but you don’t have to wait till dusk to see the pair. Why not try and spot them in binoculars before sunset?

See if you can spot Venus in the daytime today using the moon as your guide. All you need is a pair of binoculars. If your sky's really clear, Venus will be visible with the naked eye. Time shown is CDT. Created with Stellarium

The moon is fairly easy to see in a clear sky by late afternoon and early evening. Once you find it, take a look through binoculars and you’ll have no problem seeing Venus not far to its upper right. Seeing Venus in a sunlit sky can be challenging, but with the moon nearby you’ve got the cosmos on your side. Give it a try. I think you’ll be surprised how easy it is. And once you’ve spotted the duo in binoculars, take the next step and try to pick out Venus with your naked eye.

The maps show the pair for the central U.S. If you live on the East Coast, Venus will be a tad higher to the right; for the West Coast they’ll be more “level” or in line with each other.

Excellent cloud details show up in this photo of Venus taken on March 24, 2012. Credit: George Tarsoudis

George Tarsoudis of Greece took a wonderful image of Venus that shows far more detail than what you’d see with your eyes through any telescope. Using a digital camera and ultraviolet filters on his 10-inch scope, he captured textures in the planet’s clouds not visible in everyday “visual” light.

Even to the most seasoned observers rarely see detail in Venus’ clouds due to their extremely low contrast. His photo reminds me of the images taken by the Pioneer Venus Orbiter spacecraft in 1979.

Alien planets for May nights

While 522 exoplanets have been discovered so far, we only have photos of about a half-dozen. The star pictured above is HR 8799. It's 130 light years from Earth and 1.5 times more massive than the sun. It's been obscured to better show the three planets - b,c and d - in orbit about it. Credit: C. Marois et. all, NRC Canda

I’ve been reading a great new book about the history of discovery of exoplanets – planets revolving around stars beyond the sun – called Strange New Worlds – The Search for Alien Planets by Ray Jayawardhana.

The three primary ways astronomers detect other planets is by measuring the small gravitational tugs they produce on their host stars revealed through the shifting patterns of light in the stars’ spectra, transits or mini-eclipses across the face of their host stars that cause a tiny but measurable drop in the star’s light and microlensing.

We examined microlensing last week when the topic of ‘free-floating’ planets came up. When a star lines up precisely with a distant background star, the foreground star acts like a lens and magnifies the light of the distant one, briefly making it much brighter. A planet orbiting the foreground star will cause deviations in the light that betray its presence.

To date, 522 alien planets have been discovered, most them through gravitational tugging, better known as the ‘radial velocity’ method. The planet in effect tugs the star forward and then backward during it orbital revolution causing a small change in the star’s velocity toward and away from Earth. Jupiter, the biggest planet in our solar system, shifts the sun to and fro by 40 feet per second, a very tiny amount.

"Hot Jupiters" are the most common type of alien planet discovered. They're big enough - and close enough - to produce measurable tugs on their host stars. Most orbit closer in than Mercury does to the sun, making their sun-facing sides exceedingly hot.

It should come as no surprise that the larger and closer an extrasolar planet is to its host star, the greater its gravitational pull will be and the larger it will appear during a transit. That’s why most of the new planets are Jupiter-sized or larger and located very close to their host suns. They’re the easiest planets to see because their effects are the most obvious. Although our instruments are extremely sensitive, exoplanet detection is still in its infancy. The first planet around a sun-like star was only discovered in 1995.

The smallest exoplanet found so far is Kepler 10-b which is only 1.4 times the size of Earth. As methods and instrumentation improve, we’ll soon be finding more earth-sized rocky planets. Already, astronomers have come up with clever ways to detect chemicals in a planet’s atmosphere. During a transit, a bit of the star’s light passes through the planet’s atmosphere and leaves a ‘fingerprint’ on its light. When the planet has finished its pass in front of the star, astronomers then measure the star’s light alone. Subtracting the two tells them what chemicals the planet’s atmosphere contribute to the light. Sodium, carbon monoxide and hydrogen are some of the materials they’ve found.

Four stars with planets are visible in the southern sky at nightfall. The brightest and easiest in the spring sky is the star Gamma in Leo the Lion. It's orbited by the planet Gamma 1 Leo b that packs nine times the mass of Jupiter and goes around once in 428 days. Maps created with Stellarium

With all these new planets popping up, I thought it would be fun to comb through the list to see which planet-hosting stars are visible with the naked eye on late May nights. I was pleasantly surprised to find 11 stars – two with multiple planets – that were brighter than the standard rural sky limit of magnitude 6.0.

Turning to face the northwest at nightfall, Gemini, Cancer and Ursa Major (UMa) all sport exoplanets. The planet 47 UMa b is a triple planetary system, while 55 Cancri has five in all!

While the planets themselves are utterly invisible – like trying to see a firefly next an arc light 1,000 miles away – we can see the stars well enough. One of them, Gamma Leonis, is even bright enough to see from a city. All the others are visible to varying degrees depending on your sky. Binoculars will show them all with ease.

Four additional stars greet sky watchers facing north in late May. The second brightest planet-bearing star in the spring sky is Gamma Cephei, located below the North Star.

The next time it’s clear and you have a chance to go outside, see how many of these planet-bearers you can see for yourself. To help you picture the invisible worlds in orbit, consult the list below for details. Planets take their star’s name with the letter ‘b’ appended for the first planet discovered followed by ‘c’, ‘d’, etc. if additional ones are found.

Southern sky
* Gamma 1 Leo b  / 8.8 Jupiter-mass planet orbits 1.2 x Earth’s distance in 428 days / Star brightness or magnitude is 2.0 – bright!
* 70 Vir b / 6.6 Jupiter-mass planet orbits 0.5 x Earth’s distance in 117 days / Star mag. = 5.0
* Tau Boo b / 4 Jupiter-mass planet orbits 0.046 x Earth’s distance in 3.3 days / Star mag. = 4.5
* Kappa CrB b / 1.8 Jupiter-mass planet orbits 2.7 x Earth’s distance in 1191 days / Star mag. = 4.8

Western sky
Tau Gem b / 18 Jupiter-mass planet orbits in 305 days / Star mag. = 4.4
* 55 Cnc b, c, d, e, f / range of 0.03 to 3.8 Jupiter-mass planets orbiting from 0.02 to 5.8 x Earth’s distance in 0.7 to 5218 days / Star mag. = 6.0
* 47 UMa b, c, d / 0.5 to 2.5 Jupiter-mass planets orbiting from 2 to 11.6 x Earth’s distance in 1078 to 14,002 days. / Star mag. = 5.0

Northern sky
* 4 UMa b / 7 Jupiter-mass planet orbiting 0.9 x Earth’s distance in 269 days. / Star mag. = 5.8
* 11 UMi b / 10.5 Jupiter-mass planet orbiting 1.5x Earth’s distance in 516 days / Star mag. = 5.0
* Gamma Cep b / 1.9 Jupiter-mass planet orbiting 2x Earth’s distance in 903 days / Star mag. = 3.0
* 42 Dra b / 3.9 Jupiter-mass planet orbiting 1.2x Earth’s distance in 479 days / Star mag. = 4.8

Saturn’s violent storm rages on

If you're an early riser like some runners I know, see how many of the planets you can spot before sunrise. Jupiter is easiest, followed by Venus, Mercury and faint Mars. Binoculars help! Map: Stellarium

It’s still a traffic jam of planets in the morning sky, the longest I can recall in years. Depending on your latitude, it’s more or less easy to see up to four planets gathered in the eastern sky about 1/2 hour before sunrise. The map at left shows the scene tomorrow morning.

For folks living in the northern U.S., Europe and Canada, they’re all quite low, requiring haze-free skies and a clear horizon view to see. In Duluth in particular, I can happily recommend Lake Superior as the place for a.m. planet watching. The farther south you live, the better placed Mars, Mercury, Venus and Jupiter become. Best is the southern hemisphere, where the four planets line up almost straight up in the east before sunrise.

The 'Spring Triangle' is high in the south at nightfall in late May. One fist held at arm's length separates Spica and Saturn. The other two sides of the triangle are about '3 fists' long. Photo: Bob King

Saturn is still the only evening planet. Along with its bright neighbors Spica and even brighter Arcturus, it’s part of a ‘spring triangle’ that dominates the southern sky at nightfall. Without interference from moonlight, I was pleasantly surprised last night to see how bright this trio appeared.

We’ve followed the progress of Saturn’s monster northern hemisphere thunderstorm on several blogs since it exploded on the scene in December 2010. Super storms like these are rather rare with only six recorded since 1876. But what they lack in frequency they make up in intensity.

The current storm now reaches completely around the planet, measuring some 223,000 miles long. To put that in perspective, imagine a line of swirling clouds, blizzards of ammonia ice crystals and torrential winds stretching from Earth almost to the moon!

“Our new observations show that the storm had a major effect on the atmosphere, transporting energy and material over great distances – creating meandering jet streams and forming giant vortices – and disrupting Saturn’s seasonal [weather patterns],” according to Glenn Orton, based at NASA’s Jet Propulsion Laboratory and co-author of a recent paper about the upheaval.

This colorized picture of Saturn taken in three wavelengths of infrared light by the orbiting Cassini probe shows large amounts of ammonia ice particles dredged up by the storm, shown in yellow. Credit: NASA/JPL/Univ. of Arizona

Yeah, this is a biggie. Powerful updrafts from the storm pulled ammonia gas from 30 miles beneath the visible cloud deck into the bitter cold upper atmosphere, where it condensed into large ice crystals. Winds and associated storm clouds punched through the cloud tops with such force they penetrated Saturn’s normally serene stratosphere.

“On Earth, the lower stratosphere is where commercial airplanes generally fly to avoid storms which can cause turbulence,” says Brigette Hesman, a scientist at the University of Maryland in College Park and second author on the paper. “If you were flying in an airplane on Saturn, this storm would reach so high up, it would probably be impossible to avoid it.”

In this May 18 photo, the storm is the white band near the top split in two by a thin darker cloud belt. The warmer-toned belt below the storm is Saturn's North Eq. Belt. Credit: Efrain Morales

According to NASA, it’s the most violent event ever observed at Saturn by an orbiting spacecraft. Seeing this violence in amateur telescopes takes persistence because its appearance is subtle and requires high magnification (200x and up) and a night of very calm, steady air to see. Look for a pale white zone bordering the length of Saturn’s grey-toned North Equatorial Belt.

To help you find it, use this much smaller version of Efrain’s photo at right. I’ve taken and flipped it, so south is up the way you’d see it in most telescopes. The view simulates about how the planet appears on a steady night when magnified around 250x. Good luck telescopic observers!

Does the Milky Way harbor billions of orphaned planets?

This week's full moon provided the illumination for a photo of the Big Dipper (top) above a stand of poplar trees. Details: 16mm lens at f/2.8, ISO 400 and 20-second exposure. Photo: Bob King

How many planets do you think are in this photo? At least hundreds of thousands according to a new joint Japan-New Zealand survey that scanned the center of the Milky Way in 2006-2007 looking for spikes in the brightness of distant stars that reveal the presence of planets.

A planet or other large body passing directly between the Earth and a distant star acts like a lens and briefly causes the star to surge in brightness. Credit: U. of Notre Dame

The gravity of a passing planet or star warps the light of the background star, causing it to magnify and brighten. Stars warp the light of the background star to a greater extent, resulting in brightening events that can last weeks. Small planet-size bodies will cause less of a distortion, and brighten a star for only a few days or less. By measuring the the range and change in brightness over time, astronomers can estimate the size and mass of the object. It’s called gravitational microlensing and related to the warping effects of matter on space that we explored in a blog last month.

Astronomers used the 5.9-foot telescope at the Mount John University Observatory in New Zealand to regularly scan the star-rich center of the galaxy for microlensing events as part of the Microlensing Observations in Astrophysics or MOA survey. The more stars it could stare at, the greater probability of finding lensing events caused by free-floating planets.

These ‘free agents’ roam the galaxy unattached to a parent star. Either they were kicked out at birth by tortuous gravitational interactions with other planets orbiting their birth star or they formed freely by themselves, condensing from dust and gas into planet-sized brown dwarf stars or giant Jupiter-sized planets.

Free-floating planets might be common in the galaxy. Rather than orbit a host star, each would follow its own track around the center of the Milky Way. Credit: NASA/JPL-Caltech

Scientists detected 10 probable free-floaters in the survey with roughly the mass of Jupiter at distances of 10,000 to 20,000 light years from Earth.  Based on their results and theories that predict even more Earth-sized planets being ejected than large ones, the group estimates that loner planets are as common as the more familiar orbiting variety. That adds up to hundreds of billions of orphaned planets in our galaxy alone -  twice as many as the stars themselves!

The question naturally arises whether a solo planet without a star to warm it up might still potentially harbor life. All depends. If it’s large enough, the heat created during its formation through gravitational contraction could persist for billions of years. Though their cloud tops are bitter cold, deep down, the distant giants Jupiter, Saturn and Neptune are still hot enough to emit more heat than they receive from the sun. Even solo orbs might offer a foothold for life in their deep interiors. Life’s insidious that way.