We interrupt this program with a special weather bulletin from Uranus

Infrared images of Uranus obtained on Aug. 6, 2014, with the 10-meter Keck telescope. The white spot is an extremely large storm that was brighter than any feature ever recorded on the planet in the 2.2-micron (infrared) band. The cloud rotating into view at the lower-right limb grew into the large storm that was seen by amateur astronomers at visible wavelengths. Credit: Imke de Pater (UC Berkeley) and Keck Observatory images

We’ve had a few good blows this fall but none compare to what’s underway on the solar system’s seventh planet. Storm clouds have billowed up on Uranus over the past several months, so big and bright that even amateur astronomers have photographed them.

“The weather on Uranus is incredibly active,” said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and leader of the team that first noticed the activity when observing the planet with the 10-meter (393.7-inch) Keck telescope in Hawaii.

Animation showing the movement of the bright spot as Uranus rotated over a two-hour period on Oct. 4, 2014. The infrared images were taken at the Pic du Midi telescope in the French Pyrénées. Courtesy of Marc Delcroix and F. Colas (S2P)

How big is this bad boy? Observing at a variety of wavelengths, the Hubble Space Telescope tracked multiple storm fronts extending over a distance of more than 5,760 miles (9,000 km) and clouds at a variety of altitudes. That’s nearly a fifth of the planet’s 31,518 mile-diameter!

Uranus, four times the size of Earth and nearly twice as far from the Sun as Saturn, is a bitter cold planet rich with water, methane and ammonia ice in its interior swaddled in an atmosphere of hydrogen and helium with just enough methane to give it a blue tint.

Uranus photographed in September 2010 when few features were visible. Outside of a bright polar region, the planet usually appears bland in even large amateur telescopes. Credit: Damian Peach

Through a telescope, Uranus is normally a featureless dot that few amateurs astronomers bother to photograph. But once news of the storm got out, French amateur Marc Delcroix used the 39-inch (1-m) Pic du Midi telescope to give it a try. He nailed it on the second night out:

“I was so happy to confirm myself these first amateur images on this bright storm on Uranus, feeling I was living a very special moment for planetary amateur astronomy.” said Delcroix, who works for an auto-parts supplier in Toulouse, France. Anthony Wesley of Australia also succeeded in photographing the storm on September 19th and October 2nd with his 16-inch reflecting telescope. I’ve not heard whether anyone has actually seen it. Perhaps it might be possible with a large amateur scope, the right filter and a darn good night.

images of Uranus on Sept. 19 and Oct. 2, 2014 showing the dramatic appearance of a bright storm on a planet that normally displays only a diffuse bright polar region. Credit: Anthony Wesley, Murrumbateman, Australia

Bright clouds seen by amateurs and pros alike are probably caused by gases such as methane rising in the atmosphere and condensing into highly reflective clouds of methane ice.

De Pater and team detected eight large storms in all in Uranus’s northern hemisphere when observing the planet with the Keck Observatory on Aug. 5 and 6. Interestingly, the extremely bright storm in the Keck photos is not the one seen by the amateurs, which is much deeper in the atmosphere, below the uppermost cloud layer of methane ice crystals. Clearly, this Uranian hurricane rages at multiple levels in the planet’s atmosphere.

Because Uranus has no internal source of heat, its atmospheric activity was thought to be driven solely by sunlight, which is now weak in the northern hemisphere. Had it occurred during during Uranus’ every-42-year-equinox in 2007, when the Sun shined directly over the equator, no one would have been surprised, but what could cook up a meteorological megastorm with little input from the Sun is anyone’s guess.

“The colors and morphology of this cloud complex suggests that the storm may be tied to a vortex in the deeper atmosphere similar to two large cloud complexes seen during the equinox,” said Larry Sromovsky, de Pater’s colleague and planetary scientist at the University of Wisconsin-Madison. So the storm may have deeper roots. Yet Uranus is the coldest planet in the solar system, even colder than Neptune, which radiates 2.6 times the energy it receives from the Sun into space. Uranus hardly leaks at all.

Cutaway showing the structure of the planet Uranus. Wikipedia

Maybe the storm is a dust devil writ large, where warmer and denser air from the lower atmosphere suddenly rises through cooler, low-pressure air higher up and begins to rotate when conditions are just right.

“These unexpected observations remind us keenly of how little we understand about atmospheric dynamics in outer planet atmospheres,” wrote De Pater and team in their report. Still, it’s nice to know the team’s willing to put up with years of bland to wring a new discovery now and then.

Poor Uranus – we won’t forget you, I promise

Uranus and Earth compared. Uranus has an atmosphere of hydrogen and helium with clouds of ammonia and methane. It’s the methane that gives the planet its characteristic aqua color. Although little more than a dot in the sky, the planet’s 4 times larger than Earth. Credit: NASA

Poor Uranus. So dim it barely gets noticed. A lost soul. But every year at opposition, it’s nice to give the 7th planet its due. Uranus will be closest to the Earth on Tuesday October 7 at “just” 1.8 billion miles (2.9 billion km) or 19 times the Earth’s distance from the sun.

Understandably, the naked eye planets get most of our attention. They’re brighter, closer and bigger. We can follow them without optical aid, and when viewed through a telescope, there’s usually cool stuff to see. Mars wows with polar caps and dust storms, Jupiter shows his stripes, Venus and Mercury’s phases look like miniature versions of the moon and Saturn spins a hula-hoop.

Shoot a line from Beta Pegasi (upper right) through Gamma Pegasi and continue about one fist to the lower left to Delta Piscium. Uranus is 3 degrees south-southeast of Delta to the left of a similarly bright star. Use the binocular map below for further help. Click map for a larger version. Source: Chris Mariott’s SkyMap

Uranus at magnitude +5.7 can be seen with the naked eye just like the others if you know exactly where to look. This season it tracks slowly across the middle of Pisces the Fish below the bright fall asterism, the Square of Pegasus. Finding and following this tiny blue orb will be easier than usual thanks to a lucky alignment.

Here’s the scene in a pair of 7×35 or 7×50 binoculars. The numbers next to stars are magnitudes. Uranus, at magnitude 5.7, will slowly glide south of a similarly bright star now through December, giving skywatchers lots of time to spot and track the planet. Source: Chris Marriott’s SkyMap

Draw a line from Beta Pegasi, the upper right star in the Square, diagonally to Gamma Pegasi and continue in that direction until you bump into Delta Piscium. Uranus lies about 3º to its south in the same binocular field of view. To pinpoint the planet, use the binocular map. Right now, the planet lies about a degree to the east of a 5.7 magnitude star, its twin in brightness. Using this star as a reference, you’ll easily see Uranus’ slow westward crawl over the next three months.

With a diameter of 31,518 miles (50,724 km) Uranus is the third largest planet in the solar system after Jupiter and Saturn. Being so far away it takes 84 years to revolve once around the sun, 4 years longer than the average life expectancy of a U.S. citizen. One of my goals in life is to celebrate one complete Uranian year. Maybe even a little more.

Uranus has 27 moons in all. These are its five largest which range from 980 miles (Titania) to 293 miles (Miranda) in diameter. They’re composed of roughly half water ice and half rock. Credit: NASA

Uranus has 27 moons named after characters from the works of William Shakespeare and Alexander Pope and 13 known rings, the first of which was discovered only in 1977. NASA’s Voyager 2 spacecraft visited the planet in January 1986 and discovered 10 new moons and two new rings. A day on Uranus lasts just 17 hours 14 minutes. But the planet’s oddest trait is that it rotates on its side.

Only after 84 years would a hypothetical Uranian citizen be able to celebrate their 1st birthday. Uranus rotates on its side unlike the other planets with each of its four seasons lasting 21 years. It will be fall in the planet’s northern hemisphere until the 2028 winter solstice. Credit: Nature of the Universe with additions by Bob King

All the other planets have tilted axes but they rotate right side-up generally perpendicular to the plane of the solar system. Not wayward Uranus. With an axis tilted at 98º, it rotates on its side like a bowling ball! This makes for curious seasons. Since Uranus takes 84 years to orbit the sun, each of the planet’s poles gets 42 years of continuous sunlight during the summer season followed by 42 years of winter darkness.

The sun seen from the equator of one of Uranus’ moons during the northern “summer years”. It would circle the north celestial pole every 17-plus hours. Credit: Kurdistan Planetarium

Seen from Uranus (its cloudtops at least – below that it’s permanently overcast), as northern spring progresses toward summer, you’d see the sun the move in ever tighter circles toward the planet’s north celestial pole. On the solstice, the sun would be just 8º from the celestial pole and circle it once every Uranian day (17-plus hours). Then the sun would spiral out from the pole over the next 21 years until it finally set, not to return to view for another 42 years. Bizarre.

Astronomers think that long ago Uranus was struck by an Earth-sized planet at an angle that effectively tipped it over on its side like a well-placed football tackle.

Any telescope magnifying 100x or higher will show the planet as a tiny pale blue disk. Because Uranus’ atmosphere is almost featureless, higher powers and larger telescopes reveal little more on the planet. Not so the moons. Four or five are visible in 10-inch and larger scopes with Titania and Oberon the easiest. Were it not for the glare of the planet, an 8-inch would suffice. If you’d like to give the moons a try, Sky and Telescope has a very nice Javascript utility Moons of Uranus to pinpoint them at any time.

Uranus will be a snap to see in binoculars just east of the totally eclipsed moon for much of the central U.S. Wednesday morning October 8. It will be even closer (just below the moon) for observers in the western states. This simulated binocular shows the pair around 5:30 a.m. CDT. Source: Stellarium

The best time to view Uranus is without a bright moon nearby. Since the moon is now near full, you’ll want to wait a few nights to make your first observation. But Wednesday morning’s total eclipse offers an exceptional opportunity.

Because the moon’s light will be quenched during total eclipse, you’ll be able to spot Uranus with ease in binoculars about a degree to the left or east of the moon.

Anticipating Wednesday’s awesome lunar eclipse

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Struggled to find Uranus? Let the moon take you there tonight

Once you’re done chuckling, we’ll move on. Ahem!

The waning gibbous moon will near the planet Uranus tonight September 10, 2014. From northeastern U.S. it will be covered by the moon. These views show moon and planet from Syracuse (eastern U.S.) and the Midwest at the times shown. Source: Stellarium

If you’ve ever had trouble finding the remote planet Uranus, Luna can help you tonight. The waning gibbous moon will occult or cover up the planet for observers in northeastern North America, Greenland, Iceland and northern Scandinavia around 8 p.m. Eastern Daylight Time this evening.

If you have a small telescope, you’ll be able to watch the bright eastern (left) edge of the moon slowly approach and then hide the planet. Unlike a point-like star, which winks out in a split second when covered by the moon’s edge, Uranus shows a small disk and will fade more gradually over several seconds.

Observers in the wedge-shaped zone that spans the Northeastern U.S., Canada and other northern countries will see the moon cover Uranus. Those living in the U.S. and Canada will spy the planet very close to the moon’s west rim. Credit: USNO

But let’s say like me you live outside the occultation zone. What will we see? From the Midwest, Uranus will be just less than 1° to the west (right) of the moon as it comes up in the eastern sky in late twilight. Over the hours, it will appear to move gradually drift to the west away from the moon as the moon moves eastward in its orbit.

The farther west you live, the farther Uranus will be from the moon’s western edge. But not too far. Even from the California Coast, Uranus strays only about 2° (four moon diameters) to the right of the moon.

The planet may even be easier to see in binoculars from points west because it will be further from the lunar glare. No matter what, it’ll be easy to find the planet, which shines around 6th magnitude.

The view from the U.S. West Coast around 10 o’clock local time tonight. Source: Stellarium

Remember, you’ll need 50 mm binoculars, or better, a small telescope, to view the planet near the moon. Telescope users are encouraged to crank up the magnification and see Uranus’ diminutive disk next the moon, which appears gigantic in comparison. In reality, the 7th planet is nearly 15 times as large.

Uranus only a degree east of the totally eclipsed moon seen from the Midwest on October 8, 2014. Stellarium

Get ready for an even better shot at seeing Uranus. On the morning of October 8th, the full moon will be in total eclipse and the planet will lie very close due east. With no glary moonlight and everyone focused on the eclipse, more people will probably see Uranus at one time than perhaps any time in history.

Planetary oddball Uranus tempts skywatchers on October nights

Uranus is one of the two “ice giant” planets, edging out Neptune as the third largest planet. Its atmosphere is mostly hydrogen and helium with enough methane to tint the planet blue. Deep inside, Uranus has a rocky core surrounded by a thick rind or slushy ice. Uranus is “only” 1.77 billion miles from Earth this October. Credit: NASA/ESA/L. Sromovsky

This week, Thursday to be exact, the planet Uranus and Earth will be at their closest for the year. This special day is called opposition and refers to Uranus appearing opposite the sun in the sky. When the sun sets, the 7th planet will crest the eastern horizon, arc across the sky the entire night and then set at sunrise.

When planets are at opposition they’re not only closest but brightest. Bright of course is a relative term. Mars at opposition can become much brighter than Sirius, the brightest star. Uranus shines meekly at magnitude 5.7 slightly above the naked eye limit. On dark nights if you know exactly where to look, you can glimpse the planet without optical aid. I’ve seen it many times; my hope is that with the help of these maps, you will too.

Engraving of 18th century astronomer William Herschel in his element.

English astronomer John Flamsteed was the first to see Uranus in 1690 but thought it was just another star in the constellation Taurus. He even gave it a name: 34 Tauri. Despite running across it at least six times he never realized he was looking at a planet and not a star.

Enter William Herschel, a German transplant living in Bath, England and passionate sky watcher who never missed a clear night. From his garden on 19 New King Street, he stumbled across what he thought was a new comet in Taurus in his homemade 6-inch reflecting telescope on Tuesday night March 13, 1781. Closer examination of the object at high magnification showed it as a fuzzy disk, distinct from the point-like stars.

Extract from William Herschel’s journal entry made on March 13, 1781. The second paragraph reads: “In the quartile near Zeta Tauri the lowest of 2 is a curious either nebulous star or perhaps a Comet.” Source: Journal of the Royal Astronomical Society

Like any good comet hunter then or now, Herschel returned to his “comet” several nights later on the 17th to see if it had moved. For all practical purposes stars are fixed, but planets and comets inch across the sky as they orbit the sun. They can’t help but give themselves away.

Herschel next reported his find to England’s Royal Astronomical Society so others could see and track the new object. Very soon, astronomers realized this was no comet but a brand new planet, the first discovered since antiquity.

Because its axis is tipped 98 degrees, Uranus orbits the sun spinning on its side. The poles alternately face the sun for 42 years at a time. Credit: Nature of the Universe

And what an odd planet! We now know that Uranus is not only the coldest planet in the solar system – even chillier than more distant Neptune – but the only one that spins on its side. Like Earth, most of the planets spin like tops with their rotation axes tilted a little this way or that, but Uranus takes it to the extreme with a tip of 98 degrees. Seen from afar, it looks like a ball rolling on its side, and that has some curious consequences when it comes to seasons.

Since Uranus takes 84 years to make one spin around the sun, each of the planet’s poles gets 42 years of continuous sunlight during the summer season followed by 42 years of winter darkness. The northern hemisphere currently faces the sun with the first day of Uranian summer due in 2028.

Because of the planet’s extreme axial tilt, we see Uranus from different perspectives over its 84-year orbit. Right now the view is “opening up” again after a near “edge-on” view in 2006. Credit: NASA/ESA/G. Bacon – STScI

“Day” is something of a misnomer. A day on the planet lasts a little more than 17 hours, but as seen from the poles, a day in the traditional sense lasts 42 years. If you could hang out at one of the poles, the sun would rise on the first day of spring, creep slowly across the sky and finally set on the first day of fall 42 years later.

Uranus comes up into view around 9:30 p.m. local time in the southeastern sky below the Great Square of Pegasus and to the right of the small constellation Aries. It’s not far from the star Delta in Pisces. Once you find Delta with eye and binoculars, you’re ready to use the detailed map below. All maps: Stellarium

Uranus is the third largest planet, edging out distant Neptune by just 85 miles. All the large outer solar system planets radiate heat from their cores which are still contracting under the force of gravity since their formation 4.5 billion years ago. Contraction creates heat which escapes the core and spills into space.

Delta heads up a little row of stars that points toward the planet Uranus. If you place Delta to one side of your binocular view, you’ll see Uranus near the other side. The planet is the same brightness as the 5.7 mag. star. Positions are shown every 5 days from Sept. 30 to Oct. 15.

Oddball Uranus gives off little internal heat and no one’s sure why. Temperatures as low as -371 degrees F (-224 C) have been recorded in its lower atmospheric layers. Scientists hypothesize that there might be some sort of barrier deep below the atmosphere that blocks heat coming from the core. That or the planet was struck by another developing planet long ago, causing it to expel its internal heat as well as knocking the axis kittywampus.

Uranus and a few of its moons as seen in the Hubble Space Telescope. The planets also has at least 13 very narrow rings composed of water ice coated by dark, organic materials. Credit: NASA/ESA

While Uranus may be challenging to see with the naked eye, it’s easily visible in binoculars even in less than ideal skies. That’s the good news. The bad news is that the planet isn’t near any bright stars that would give a beginning observer a leg up in finding it. No problem. We’ll get you there anyway.

Through a telescope magnifying about 75x you can tell you’re looking at a planet and not a star. Stars are tiny and possess a fiery radiance; Uranus looks slightly larger and “dull” in comparison. Once you crank up the power to 150x and higher, you can’t miss its tiny disk, tinted blue from atmospheric methane gas. Amateur astronomers using scopes in the 12-inch to 16-inch range can even spot two of the planets 27 known moons, Titania and Oberon.

Uranus moves slowly westward through the constellation Pisces during October. You can watch its progress in binoculars as it passes among several “fixed stars” of similar brightness. Face southeast starting around 9:30 – 10 p.m. when the planet has cleared the trees and houses and begin by locating the Great Square of Pegasus, a big, vacant square of sky with a star marking each of the four corners. Drop down one outstretched fist below the Square to find the dimmer star called Delta in the constellation Pisces. Now center your binoculars on Delta and use the map below to hone in on the planet’s location.

I wish you well in discovering the 7th planet all by yourself just as Herschel once did.

Concealed planets exposed plus it’s spring break on Mars

The sun and its pack of planets photographed earlier today by the coronagraph aboard the SOHO observatory. The sun (white circle) is blocked by an opaque disk so astronomers can study the streaky solar atmosphere called the corona. Credit: NASA / ESA

Half the planets have gone into hiding. Mercury is too low in the dawn sky for northern hemisphere skywatchers, and Mars, Venus and Uranus are gathered around the sun concealed by its glare. Only Jupiter and Saturn remain available for our viewing pleasure.

Still, it’s hard to keep planets hidden away when you’ve got the eyes of the Solar Heliospheric Observatory (SOHO) on your side. SOHO orbits around a stable region of space called the L1 Langrangian point where the gravity of Earth balances that of the sun.

SOHO orbits about a million miles ahead of Earth in line with the sun in a small “halo orbit” around the L1 Lagrangian point. From this vantage point it keeps the sun and Earth in view 24/7. Credit: Office of Naval Research

From this prime observing spot, scientists use SOHO’s cameras to study the sun in many wavelengths or colors of light. Special devices called coronagraphs block the overly-bright solar disk with a metal stop to allow viewing of the sun’s outer atmosphere or corona. They also show other objects in the field of view like comets and the current gang of planets – Uranus, Venus and Mars.

Since the planets are very near one another, lots of interesting lineups will happen in the coming days. Venus reaches superior conjunction on March 28 (tomorrow) when it lines up on the opposite side of the sun from Earth. Six hours later it’s only one degree (two full moon diameters) below Uranus. An hour after, Uranus is in conjunction with the sun. Then on April 6-7 Venus and Mars will be in conjunction just half a degree apart. Is this beginning to sound like a barn dance?

One thing to remember about conjunctions – the planets involved are not physically close; they only appear to be because we see them in the same line of sight. If you’d like to watch all these interesting encounters, check out SOHO’s latest coronagraph image.

Approximately every 26 months, Mars passes almost directly behind the sun from Earth’s perspective. During this time, NASA will halt communications with the two rovers. Credit: NASA/JPL-Caltech

For us, Mars’ proximity to the sun is interesting but inconsequential. Not so for the Curiosity mission. On April 17 the planet is in conjunction on the opposite side of the sun from Earth. From our perspective, Mars will appear extremely close to the sun’s brilliant disk. Radiation from solar flares and high-speed subatomic particles in the sun’s corona can disrupt radio transmissions between the two planets during close alignments like this one. To prevent compromised radio commands from reaching either Curiosity or the older Opportunity rover, mission controllers will temporarily suspend transmissions from April 9 to 26.

Wide angle view of Yellowknife Bay taken by one of Curiosity’s hazard avoidance cameras on March 27, 2013. The rover recently resumed science operations after recovery from a computer glitch. Credit: NASA/ JPL

Communications from Mars to Earth will also be reduced. To stay in touch, Curiosity will send daily beeps to Earth. Meanwhile both rovers and orbiting Mars satellites will continue science operations. Data gathered will be stored and then beamed to Earth in early May. The rovers’ spring break will be tame by earthly standards; both will stay put during the interval to prevent any shenanigans.

The bright star Sirius and planet Jupiter perform a balancing act on either side of Orion’s Belt this month and next. This may shows the sky facing southwest around 8:30 p.m. in late March.  Maps created with Stellarium

Did I mention there are still two great planets out at night? Jupiter stands high in the west-southwest at nightfall. It’s the brightest object in that direction. Saturn comes up later around 11 o’clock in the southeast about one extended fist to the lower right of Spica. The full moon will be near Spica tonight and Saturn on Thursday night. Much to see for all!

The full moon will swing by both Spica (tonight) and the planet Saturn tomorrow night. This map shows the sky facing southeast around 11:30 p.m.

Uranus makes a rare pass by a star in Pisces

To get oriented, face east around 10 o’clock and find the Great Square of Pegasus. Uranus is located one “square width” below and in line with the Square’s left side and forms an isosceles triangle with Delta and Omega Piscium. Charts created with Chris Marriott’s SkyMap

Last week at a star party I aimed my telescope at Uranus for the first time this season and was pleasantly surprised to find it next door to 44 Piscium (PYE-see-um), a star of identical brightness. One by one people lined up for a look. We had fun comparing the two colors – Uranus an obvious blue against the yellow-orange of 44 – and trying to figure which was the planet and which the star. That was apparently too easy, since everyone had no trouble telling them apart.

As we zoom in a little, Uranus and 44 Piscium stand out better. Delta and Omega Piscium will guide binocular users to the pair. Uranus is magnitude 6 and just visible with the naked eye from dark rural skies. Stars are shown to magnitude 7 with the view facing around 10 this evening (22nd).

Since then, Uranus has been edging closer to the star night after night. Tonight (Sept. 22) and tomorrow they’ll be at their closest and form a striking “double star” through binoculars and telescopes. How close? Only 1.4 arc minutes  or about 1/20 the diameter of the full moon. Those with excellent skies will see the pair as a single, faint, unresolved star, while binoculars will show them as a pair of close-set “eyes” staring straight back at you. In the coming nights, the planet will slowly pull away to the west but remain near 44 through the end of the month. Finding the 7th planet and seeing it groove through the sky is a very worthwhile observing project that requires only the simplest of equipment.

Our final chart is close in, so you can use it to track Uranus’ movement to the right (west) over the coming nights. Positions are shown for 10 p.m. CDT. The blue dots show the planet on the nights of closest approach.

Uranus always appears identical to a star with the naked eye and binoculars, but a small telescope magnifying 60x or higher will not only show the color difference between star and planet but also reveal Uranus as a tiny disk. 44 Piscium will remain a flickering point of light even at high power – a fine side-by-side example of the difference in appearance between a star-like planet and a star. I wonder if the colors will be visible in binoculars? Only one way to find out. Good luck!

Weird Uranus auroras seen first time from Earth

Wild leeks push through the dried leaves of the forest floor each April in Duluth's Hawk Ridge nature reserve. Photo: Bob King

The ground is snapping and popping. Ever hear this? On quiet evenings in the country in mid-spring, you can walk up to a roadside ditch along the edge of the forest and listen to green plants pushing up through last year’s leaves and grasses. It sounds like fire consuming tiny twigs. Green fire.

I used to think it was insects but I’ve looked with a flashlight and heard it for so many years I’m certain the sound is from plants on their way up and out. Not even night can hold back the call of the sun.

The sun reached out to Earth this week in the form of the aurora borealis. Uranus also displays auroras but as dots instead of arcs and curtains. Auroras were seen by the Voyager 2 spacecraft during it 1986 flyby of the planet, but this is the first time they’ve been spotted from Earth.

Uranus' northern lights have an unusual form and different location compared to Earth's due to the planet's unusually large tilt and offset magnetic field. Uranus faint ring system is also seen. Credit: Laurent Lamy

Using the Hubble Space Telescope, astronomers photographed dim dots of aurora glowing above Uranus’ pale blue cloudtops. The Uranian lights last only a few minutes at a time before fading away, making them even trickier to catch than the earthly variety.

Auroras on both Earth and Uranus are produced when charged particles (electrons and protons) from the sun enter a planet’s magnetosphere or protective magnetic envelope, and are guided into the polar atmosphere by the planet’s magnetic field.

Uranus' axis is tilted almost 98 degrees. During its 84-year orbit, first the north pole and then the south pole points toward the sun. In between, one side or another faces the sun. Credit: Smithsonian

Earth’s magnetic field is tipped just 11 degrees relative to the our axis of rotation. When the solar wind hits, the particles travel toward the north and south polar regions, which is why auroras are visible in Earth’s more northern and southern locations than nearer the equator.

Uranus is another place altogether. Its rotational axis is tilted 98 degrees compared to Earth’s modest 23.5. This means the planet literally rotates on its side like a bowling ball rolling down a lane. Its magnetic axis is way out of whack too – not only offset from the planet’s core but tilted 60 degrees relative to the rotation axis. Back during the Voyager 2 flyby, the planet’s south pole was pointed toward the sun with the magnetic poles far off to the sides. Voyager observed auroras on Uranus’ nightside resembling those on Earth.

The Earth, with its modestly-tipped rotation axis (blue arrowed line) and nearly north-pointing magnetic field axis, is a far cry from the extremes of Uranus.

Uranus has since moved along its orbit so that now its side faces the sun instead of a geographic pole. This happy circumstance means that one of the magnetic poles points directly at the sun.

When a big blast of solar wind left the sun in September 2011, the particles sped past Earth in 2-3 days, blew by Jupiter two weeks later and arrived at Uranus in mid-November, creating the odd dots of aurora that seem to lie near the equator. They’re really near the planet’s magnetic poles!

Uranus, you’re a mixed up planet, but we love you anyway. To read more about the new aurora discovery, click HERE.

Uranus passes Mercury in the dusky dusk

Mercury will be highest in the west this coming week as it slowly fades. A small telescope will show its half-moon shape. Created with Stellarium

Mars may be closest to the Earth these next few days, but Mercury’s not doing too bad either. Tomorrow it reaches it greatest elongation east of the sun in the evening sky. Provided you’ve got a decent view to the west, you should have no problem seeing the planet starting around 45 minutes after sunset, when it’s almost an outstretched fist high in the western sky. Follow the line from Jupiter and Venus down toward the horizon to point you in the right direction.

Both Mercury and Venus are showing “half moon” phases. Venus’ shape is easier to see because the planet appears almost three times larger in a telescope. Mercury travels in a tight, fast orbit around the sun and goes through phases much faster than more distant Venus. In just a week, it will have narrowed to a crescent. We’ll have to wait until the end of April before Venus is a similar crescent.

How Mercury and Venus will look through a small telescope this weekend. Created with Chris Marriott's SkyMap

Remember the Venus-Uranus match up early last month when the two planets were simultaneously visible in the same binocular field of view? I’ve got good news. It’s happening again tonight through Monday, but this time it’s Mercury’s turn. So if you missed the February opportunity to see Uranus because of clouds or commitments, and you’re up for a challenge, here’s a second chance.

Mercury and Uranus will pass each other this weekend. Uranus moves little - it's a distant planet - while Mercury moves upward. The map shows the sky facing west with north to the right. Stars are drawn to mag. 7.

These planet “handoffs” remind me of a high school relay race, where one runner passes the baton to a teammate, who runs a set distance before handing it to the next. Uranus is the baton in this interplanetary relay.

You’ll need very clear, dark-as-possible skies and 7×50 or 10×50 binoculars to see Uranus, because twilight will interfere much more than it did last month. It helps that both fit comfortably in the same field of view of most binoculars. Consider using a small telescope if you don’t succeed with binoculars.

Today they’re 3 degrees apart; tomorrow a tad closer. Closest approach of 2.5 degrees happens Monday morning in the daytime sky. Good luck – this could be a tough one. But what is life without the occasional astronomical challenge?

There’s more to Orion than 3 stars in a row

Venus and Uranus slowly separate but remain near enough to one another to easily fit inside a binocular view (yellow circle). The maps show the sky as you face west in late twilight. Stars shown to ~6.5 magnitude. Created with Stellarium

Some of us had cloudy skies last night and couldn’t see the conjunction of Venus and Uranus. Well, I’m here to tell you there’s still hope. The two will be close enough the next couple nights to easily see together in the same binocular field of view. Just use the little maps above to guide you. Conveniently, Uranus is directly below Venus tonight.

Orion painted in gold on a living room ceiling. Photo: Bob King

While I was on assignment shooting photos for the Duluth News Tribune this week, I came upon a star-studded ceiling in a subject’s living room. Orion, Cassiopeia and the Big and Little Dippers were painted in gold against a robin’s egg blue.  I felt right at home.

Orion is beautifully placed in mid-February straight up and high in the south around 8 p.m. local time. The three belt stars are the easiest to see, but there’s a good deal more to the constellation you may not have been aware of. The rectangular box of stars centered on the belt forms the general outline of the Hunter. Bright red Betelgeuse marks the top of his shoulder and equally brilliant Rigel his left foot.

If you can escape city light pollution, you’ll see plenty more of Orion beyond his bright frame. Look for his sword directly below the belt, the upraised club in his right hand and curved shield in his left.

A delightful bit of fuzz awaits your eye smack in the center of the sword – the Orion Nebula. Visible to the naked eye as a hazy spot, binoculars will show a small cloud studded with several bright stars. These stars – and thousands of others buried inside the mist – formed from the gravitational attraction of gases. They’re literally newborns compared to most of the stars visible to the naked eye.

Orion represents the mythological Hunter figure. He comes equipped with the best equipment of the era of his creation thousands of years ago. Click photo to learn more about the constellation. Picture at right: Bob King

I’ve always found it funny that for so grand a figure as Orion his head is so tiny, but that’s the way things go when you’re creating constellations – you use what you’ve got at hand.