Mercurial delights / Supernova in spiral galaxy M61 / Jupiter spots

Mercury shines brightly in the east-southeast more than an hour before sunrise this morning November 1. The planet remains well-placed for viewing for the coming 10 days. Credit: Bob King

Scattered thin clouds took nothing away from this morning’s otherwise clear sky. With the Moon waxing from quarter to gibbous phase, the slab of darkness between moonset and dawn gets sliced thinner every day. Starting November 4th the Moon will light the sky all night and not give back the darkness till next weekend. I took advantage of a moonless morning to set up the telescope to view two comets, a brand new supernova in the bright Virgo galaxy M61 and the planet Mercury at dawn.

Around 7 a.m. CDT (6 a.m. CDT) in bright twilight, Spica cleared the treetops about 5 degrees to the lower left of Mercury. Watch in the coming mornings as Spica slides up higher in the sky and Mercury slowly drops horizon-ward. Credit: Bob King

Normally I suggest looking for Mercury around 45 minutes before sunrise when it’s high enough for a good view, but if you have an wide open eastern horizon, go for it earlier. The planet is very bright right now at magnitude -0.6 — brighter than it’s nearest rival, Arcturus (0.0) located three outstretched fists to the upper left of Mercury. I was surprised at how bright and easy it was to see it more than an hour before sunrise.

In the next few mornings, Virgo’s brightest star Spica rises near the planet. Watch them do a do-si-do in the coming days as Spica passes Mercury.

Facing east about 50 minutes before sunrise tomorrow and Monday Nov. 2-3. Mercury will be near Spica and about three outstretched fists to the right and below Arcturus. Source: Stellarium

Gianluca Masi captured this view of the supernova 2014dt (tick marks) in the 9th magnitude barred spiral galaxy M61 in Virgo on Halloween. The galaxy is some 55 million light years from Earth. Credit: Gianluca Masi

Virgo brings more than a bright morning planet. Tucked with the broad “Y” or cup-shaped northern half of the constellation, the bright galaxy M61 glows with a brand new supernova visible in amateur telescopes.

Japanese amateur astronomer Koichi Itagaki discovered the new star on October 29 at magnitude +13.6. A little on the faint side, yes, but it has been slowly brightening. This isn’t the first time we’ve witnessed a supernova explosion in the galaxy. At least two others – 2006in and 2008ov – have been observed. Quite the hotbed!

View looking east just before the start of morning twilight. M61 is located in the big Virgo “Y” about three outstretched fists to the right and above brilliant Arcturus. Source: Stellarium

Enlarged view of Virgo to help you better track down M61. When you find it, the supernova will look like a star inside the galaxy east of the core. Click for a large version. Source: Stellarium

Right now, you’ll need an 8-inch or larger telescope and dark sky to see it. The best time is just before dawn when Virgo is highest in the eastern sky. Through the eyepiece of my 15-inch (37-cm) scope this morning the galaxy glowed big and round with a bright core. Supernova 2014dt was a dim “star” 40 arc seconds east and 7 seconds south of the nucleus. Use the maps above to help you find the galaxy.

This morning’s shadow transit of Jupiter’s largest moon Ganymede (left) and a future transit that will occur on November 8 between 3:35 – 7:12 a.m. CST. The Great Red Spot will also be nicely placed for viewing. Add 1 hour for EST, subtract 1 hour for MST and 2 hours for PST. Source: Meridian

I always save the bright planets for last not only because they provide a refreshingly bright treat after hunting comets and supernovae but also because I don’t want to destroy my night vision. But I got a great surprise when pointing the scope at Jupiter. Plain as could be, there was the shadow of the planet’s largest moon Ganymede silhouetted against the white clouds of the equatorial zone and next to it, Ganymede itself. For a minute it looked like two moons casting shadows on the planet. Compared to its shadow, Ganymede was smaller and gray-toned.

You can catch the next Ganymede shadow transit visible in the western hemisphere on the morning of November 8 from 3:35 to 7:12 a.m. CST. A 3-inch or larger telescope is all it takes to view it.

The sun rises just before 8 a.m. over the Wisconsin shoreline of Lake Superior this morning November 1. Credit: Bob King

What better way to top off a morning of sky watching than with a sunrise? Now maybe I’ll take a nap.

Fleet of foot Mercury appears at dawn

Mercury comes into good view the remainder of October and the first week of November low in the eastern sky during morning twilight. This map shows the sky from the central U.S. (Champaign, Ill. in particular) tomorrow morning October 28 about 40 minutes before sunrise. Also shown is the planet’s orbital path in the sky and the bright star Arcturus, which you can use to help you find the planet. Source: Stellarium

Mercury is the solar system’s hot sports car. Not only is it the smallest planet, but it rips around the Sun once every 88 days, faster than any of the others. That’s 4 revolutions for every one the Earth makes. As you read this, Earth’s toting you around the Sun at 66,600 mph. Mercury’s got the pedal to the metal at nearly106,000 mph.

Now through the early November you have a chance to watch this speed demon in morning twilight. Six times a year the fleet planet reaches greatest elongation from the Sun, when it’s highest above the horizon during twilight and easiest to spot. This season that date is November 1st, but you can look for Mercury anytime now through about Nov. 10th.

Mercury has phases like the Moon because of the changing angle it makes to the Sun as viewed from Earth during its 88-day orbit. The dates show inferior conjunction between Earth and Sun (Oct. 16), greatest western elongation (Nov. 1), superior conjunction (Dec. 8) and greatest eastern elongation (Jan 14) when the planet returns to good evening sky viewing. Credit: Bob King

Unlike the outer planets, which orbit beyond the Earth, Mercury orbits between our planet and the Sun. That’s why it never strays far from the Sun in the sky and only puts in an appearance after sunset at dusk or before sunrise at dawn. Because it’s in such an orbital hurry, we usually only get to see the planet for a couple weeks during each favorable elongation.

Mercury shows phases like the Moon. This is approximately how the planet will appear in the next few mornings. Source: Stellarium

To the eye, Mercury looks like a fairly bright star (magnitude 0 and brightening to -0.7 in the next two weeks), but through a small telescope it shows phases just like the Moon and Venus.

Right now it’s a fat croissant but it will fill out and brighten in the days ahead.

Take advantage of the late morning sunrises in the days before we lose Daylight Saving Time to find Mercury at a reasonable hour (around 6:40-7:15 a.m. from many locations).  Look “one fist” above the eastern horizon about 45 minutes before sunrise.

 

Ever seen a lunar eclipse from Mercury? Me neither … till now


Wednesday’s lunar eclipse photographed by NASA’s MESSENGER spacecraft at Mercury

As millions of us awoke at dawn and trundled outside to watch the total lunar eclipse this week another set of eyes was keeping tabs from afar. 66 million miles away, NASA’s MESSENGER spacecraft turned its camera toward Earth to capture several images of the moon disappearing into our planet’s shadow. Laced together, they make for a brief but fascinating glimpse of planetary bodies in motion.

Two of the still images showing Earth and moon before and during Wednesday morning’s total eclipse. Credit: NASA

The animation was constructed from 31 images taken two minutes apart from 5:18 to 6:18 a.m. EDT. The images start just before the Moon entered the umbra, the darkest part of the Earth’s shadow.

“From Mercury, the Earth and Moon normally appear as if they were two very bright stars,” noted Hari Nair, a planetary scientist at the Johns Hopkins University Applied Physics Laboratory, in Laurel, Md. “During a lunar eclipse, the Moon seems to disappear during its passage through the Earth’s shadow, as shown in the movie.”

MESSENGER photographed Earth and moon on May 6, 2010 from 114 million miles (183 million km) away. Credit: NASA

Because the moon is so much darker than Earth its brightness has been increased 25 times to show its disappearance more clearly. I’ve included another picture of the Earth and moon against the starry backdrop of deep space also photographed by MESSENGER. Sure puts things in perspective. While not as breathtaking as photos of Earth taken by the Apollo astronauts, seeing our tiny home floating in the void effectively communicates how improbable our existence is. Thank goodness life got a grip and kept it. After 3.5 billion years of evolution the double helix has proven itself a force with which to be reckoned.

The 133-mile-wide double ringed crater Vivaldi captured at sunrise. The low sun highlights valleys and chains of secondary impact craters radiating away from it. Credit: NASA

MESSENGER has been in orbit around Mercury since March 2011 studying the chemical composition of the surface, measuring planet’s magnetic field, mapping polar ices and of course taking pictures. Enjoy a few recent ones.

Hollows on the floor of an unnamed crater on Mercury. Hollows may be areas “eaten away” by the ceaseless bombardment of particles in the solar wind. Or they may form when heat from volcanic activity melts away softer rocks. No one knows for sure. Credit: NASA

Come fly with me to Mercury


MESSENGER flies over Mercury. The spacecraft blasted off from Cape Canaveral on August 3, 2004.

To commemorate this week’s 10th anniversary of the launch of NASA’s MESSENGER spacecraft to Mercury, NASA released this amazing video of a flight over the planet’s north polar region. The movie was assembled from 214 images taken once per second by the probe’s narrow-angle camera on June 8, 2014. Enjoy the cratery desolation.

As the photos were snapped, MESSENGER orbited at altitudes ranging from 71 to 102 miles (115 to 165 km), traveling at a speed of 2.3 miles per second relative to the surface.

One of the highest resolution pictures ever taken of Mercury’s surface shows a field of craters only 1.8 miles (3 km) wide photographed on June 11, 2014. MESSENGER will drop down much closer to the planet – only 31 miles – starting August 19. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

“This view is what a traveler on the MESSENGER spacecraft might see during low-altitude operations in the coming year,” said MESSENGER co-investigator Scott Murchie. “During the final phase of its mission, MESSENGER’s science instruments will use low-altitude operations like this to explore the surface and subsurface of Mercury at unprecedented resolution.”

Mercury is presently too close to the sun to see safely, but on August 2 it lined up in conjunction with Jupiter as seen through the coronagraph (sun-blocking device) on the Solar and Heliospheric Observatory. Credit: NASA/ESA

Mercury orbits closest to the sun of the eight planets, completing one revolution every 88 days. It has virtually no atmosphere and measures only about a thousand miles larger than Earth’s moon.

Daytime surface temperatures there can reach 801°F (427°C). Despite the extreme heat, MESSENGER’s instruments detected water ice in permanently shadowed craters in the planet’s polar regions.

Launched in August 2004, MESSENGER traveled 4.9 billion miles (7.9 billion km) to finally settle into orbit around the speedy planet on March 18, 2011. Its convoluted journey included 15 trips around the Sun and flybys of Earth once, Venus twice, and Mercury three times. All of this was done to slow the craft down so it could enter orbit about the planet. It’s returned more than 240,000 pictures so far, many of which you can browse HERE.

Supermoon fun / Mars-Spica conjunction tonight / Venus visits Mercury at dawn

Passing clouds create a colorful corona around last night’s full moon. Credit: Bob King

The moon coaxed many of us out for a look last night. We had clear if hazy skies in my town which made for a striking display of lunar crepuscular rays. Lunar what? If you’ve ever seen sunbeams poking through clouds in the afternoon or evening, you’re looking at crepuscular rays. Crepuscular comes from the Latin word for ‘twilight’ as the beams are often noticed during early evening hours around sunset.

A delicate display of crepuscular rays radiates across the sky above a cloud-shrouded moon. Credit: Bob King

Bright rays shining through gaps in the clouds alternate with shadows cast by other clouds to form a spreading fan of light and dark columns. The dustier or smokier the air, the more vivid the crepuscular display. Notice how they appear to converge on the moon. This is an optical illusion. The rays are perfectly parallel just like endless rows of beans on a farm that appear to merge together in the distance.

Last night’s supermoon shines back from a mobile phone. I took the picture by holding the phone’s camera lens directly over the eyepiece. Credit: Bob King

Many of us like to take pictures of the moon through a telescope using nothing more than a mobile phone. If you’ve tried this, you know how tricky it is to hold the phone camera in the right spot over the telescope eyepiece. It takes a few tries, but the results can be remarkable. Phones do well on bright celestial object like the planets, moon and sun (with a safe filter). Despite what some ads might tout, phones can’t yet record fainter things like galaxies, nebulae and the like.

Orion Telescopes makes an adaptor to hold a phone securely over the telescope. While it gets mixed reviews, you might want to consider it if you don’t want to invest in a separate camera but would still like to create an album of your own astrophotos.

Mars (top) and Spica last night July 12. The difference in color between the rusty planet and blue-white star was very easy to see. Mars will remain near the star the next few nights but change its position like the hour hand on a clock. Credit: Bob King

I know we’ve all been moonstruck the past few nights, but did you happen to notice how close Mars and Virgo’s brightest star Spica have become? Last night they were separated by only 1.5 degrees; tonight they’ll be in conjunction a squinch closer at 1.3 degrees. Watch for the duo in the southwestern sky near the end of evening twilight.

Mars moves eastward and soon departs Spica en route to its next notable appointment, a conjunction with Saturn on August 25. Have you been up at 5 a.m. lately? Me neither. But my crystal ball a.k.a. Stellarium program tells me that Venus and Mercury are playing tag an hour before sunrise in the eastern sky.

Venus and Mercury shine together low in the northeastern sky during morning twilight the next couple weeks. This map shows the view tomorrow morning 45 minutes before sunrise. Venus will be about 10 degrees (one ‘fist’) high, Mercury half as much. Source: Stellarium

Mercury reached greatest elongation (distance) west of the sun yesterday and now appears about five degrees high in the northeast some 45 minutes before sunrise. Look for it about the same distance below brilliant Venus. This is a good apparition of Mercury, and having Venus nearby makes it easy to spot.

The swiftest-moving planet will hang near the goddess planet for the next two weeks, all the while growing in brightness as its phase fills out from crescent to full.

Crescent moon visits a ‘wintering’ Venus / Mercury-moon conjunction for y’all

The slender crescent moon brushes Venus Tuesday morning at dawn low in the northeastern sky. The Pleiades star cluster, better known as the Seven Sisters, floats just above the pair. This map shows the sky facing northeast around 4 a.m. June 24. Stellarium

Wonder where the moon’s been hiding lately? Unless you’re up around 3 a.m. it’s been scarce this past week. All that time our favorite cratered world has been slimming down in the morning sky.

Now it’s a waning crescent fingernail, what many consider the moon’s most eye-catching phase.

Tuesday morning June 24 at dawn the thin crescent will join Venus in the constellation Taurus just below the pretty Pleiades star cluster. About 1 1/2 degrees or three moon diameters will separate Venus and the moon. To see this beautiful conjunction, look low in the northeastern sky at the start of dawn.

For the best view of the Seven Sisters, I recommend binoculars. Whenever I’ve had a reason to be up before sunrise in early summer I make a point of looking at the cluster. Taurus, neighboring Auriga and the Pleiades all belong to the winter sky, but we get a preview of that inevitable season as early as the first mornings of summer. There’s something delicious about seeing the first stars of winter as the robins sing in the dewy woods.

An extremely thin moon will pass very close to Mercury on Thursday morning June 26 as seen from the southern U.S. This view shows the sky facing northeast right around sunrise for New Orleans, LA. The moon will only be about 5 degrees high at the time. Use binoculars to find it. Seeing Mercury will require a small telescope. Stellarium

Live in the far southern U.S.? You’ve got one more lunar visitation. This one will be challenging. On Thursday morning, the moon, just 21 hours before new, will glide a fraction of a degree south of the planet Mercury in a bright sky only minutes before sunrise. The moon will hover very low (5 degrees) in the northeast in a bright sky. Whatever you do, bring binoculars. You might need them to find the moon at all.

Like the moon, Mercury’s an extremely thin crescent and very faint, shining at just magnitude 3.5. Skywatchers might spot it in binoculars, but I’m not betting on it. With very clear skies, there’s a chance of seeing the planet directly above the northern cusp of the moon with a small telescope. Should you succeed, you’ll be rewarded with the rare sight of two delicate crescents one atop the other. Find a location with a wide open view to the northeast and start looking about 15 minutes before sunrise.

The moon will cover up or occult the planet for observers in northern South America, but again, this will happen in a bright sky and prove tricky to see.

Just a reminder. Although no auroras showed last night at mid-latitudes, there’s still a chance for a minor storm tonight. I’ll send out a notice if that happens.

 

Lunar crescent returns – Mercury and Jupiter follow mother sun into twilight

The crescent moon will be near Mercury tonight (May 30) and below Jupiter tomorrow night. The map shows the sky facing northwest about 40 minutes after sunset. Stellarium

Nice to see to moon back in the evening sky just in time for the weekend. The 2-day-old slender slip of a thing makes an appearance about 40 minutes after sunset about 7 degrees (not quite one outstretched fist) to the lower left of Mercury.

Keen-eyed observers with haze-free skies may spot the planet without optical aid, but I’m guessing it will take a pair of binoculars. Mercury has faded in the past few weeks and will soon disappear in the sunset glow not to return again for northern hemisphere skywatchers until mid-July before dawn.

You’ve probably noticed that Jupiter’s been dropping lower and lower in the west and now sets near the end of evening twilight. The hefty planet and skinny moon will line up for one last easily visible conjunction tomorrow evening. By next lunar crescent (June 29), Jupiter will be difficult to pick out from the twilight glow.

In this map I’ve removed the atmosphere and added the ecliptic, the path taken by the sun, moon and planets across the sky. The sun’s day-by-day travel to the east is a reflection of Earth’s revolution around the sun. Its movement outpaces that of the outer planets, so it gradually catches up and then passes them one after another. When near the sun, a planet can’t be seen, but when the sun has left it behind, the planet reappears to the right or west of the sun in the morning sky to start the cycle all over again. Stellarium

Because sun, planets and moon all follow the same general path across the sky called the ecliptic, they inevitably pass near the sun for at least a few weeks every year (more often for the inner planets Mercury, Venus and the moon). Solar glare renders them invisible for a time until they pop back into view in the morning sky at dawn and begin the next cycle of visibility.

Saturn disappears, Mercury appears during ‘night of the planets’


Saturn covered and uncovered by the moon earlier today by Dave Herald, Murrumbateman, Australia

Enjoy the video. Dave Herald did a great job recording this morning’s Saturn occultation. The images are very sharp. I always find it remarkable how atmosphere-less the moon is. There’s not a hint of softness in the planet as it’s devoured by the lunar limb. If there were substantial air, the planet would gradually soften and fade.

For a moon or planet to be completely without air is next to impossible. The solar wind knocks atoms from minerals on the lunar surface and sends them reeling into the virtual vacuum above the surface. Studies have found potassium, sodium, helium and argon in the moon’s exosphere, the name given to the lunar atmosphere. Bombardment of the moon’s surface rocks by micrometeorites and the solar wind release potassium and sodium; helium and argon probably bubble up from radioactive decay of those same rocks. Helium may also arrive via the sun’s wind.

Glow from sodium in the lunar atmosphere. The light from the moon has been blocked by the telescope, but the size, position and phase of the Moon are shown by the superimposed image in the center. Rayleighs are a measure of brightness. Credit: NASA

At sea level on Earth, we breathe in an atmosphere where each cubic centimeter contains 10,000,000,000,000,000,000 (10 quintillion) molecules; by comparison, the lunar atmosphere has less than a million molecules in the same volume.

Comets and meteoroids striking the surface temporarily enhance the amounts of other atoms and molecules. But the sum total of all the sputtering and interacting is an atmosphere equal to the amount of air you’ll find 250 miles high where the space station plies it orbit. Not much.

Mercury stands all by itself low in the northwest in this photo taken about 50 minutes after sunset last night. Credit: Bob King

At my house, we saw no occultation of Saturn, but the two did stand together in the southeastern sky at dusk. On the opposite end of the heavens, Mercury made a fine naked eye appearance in the northwestern sky.

Jupiter glows over Amity Creek last night. Both the creek and the sky were lit by the light of the full moon. Credit: Bob King

I first caught it around 9:15 p.m. some 40 minutes after sunset and watched it for at least a half hour. Capella and Jupiter – both higher up in a darker sky – made for great sight lines to the planet.See yesterday’s map for details.

Jupiter in Gemini remains the most brilliant object in the western sky at dusk during early evening hours. I watched it from a nearby creek that rushed with water from snow melt and recent rains.

Mars stood between Jupiter and Saturn. This week the ‘boring’ hemisphere – the one with fewest dark markings – is turned toward western hemisphere observers.

The Moon, Mars (upper right), Saturn (lower left), Spica (immediate right of moon) and Arcturus (top) as seen from Dayton, Ohio on May 12. Credit: John Chumack
Dayton, Ohio

But there’s still much to see – enough to easily stay up past your bedtime. The north polar cap on Mars remains visible despite the seasonal summer ‘heat’, and white clouds topping the planet’s major volcanoes are visible along the planet’s western edge. Check it out.

Mercury leaps into dusk – don’t miss it!

The sky facing west about 40 minutes after sunset in mid-May when Mercury will be just shy of one outstretched fist above the northwestern horizon.  It shines brightly at magnitude -0.3 this week. Use higher, brighter Jupiter to make a sight line to the planet. Mercury’s making its best evening appearance of the year for northern hemisphere sky watchers. Stellarium

Now through the end of May is the prime time to look for Mercury in the evening sky. Like the rock star Prince, this small, speedy planet is elusive, making only a few brief appearances a year.  Consider this a personal invite to the show.

To find Mercury, pick out a place with a wide open view to the west-northwest in the direction of sunset. Start looking a half hour after sundown about a fist to the left of the brightest glow left on the horizon by the setting sun. Mercury will be some 8-10 degrees (about one outstretched fist) above the horizon. It looks like a solitary diamond in twilight’s pink glow.

Mercury shows phases as it revolves around the sun as seen from Earth’s perspective outside looking in. Mercury, like Venus, appears largest when nearly lined up between Earth and sun at inferior conjunction. Planets not to scale and phases shown are approximate. Illustration: Bob King

Mercury gets easier to see as the sky darkens … to a point. Once it’s within a few degrees of the horizon, the thicker, dustier air in that direction quenches its light and the planet fades.

The one-day old evening crescent moon with Mercury (upper left) on Jan. 31 this year. Credit: Bob King

It’s amazing that Mercury’s rates as a planet considering how small it is – just 3,021 miles (4,880 km) in diameter. At 2,160 miles across, our own moon is 71% as large. Jupiter’s moon Ganymede is even bigger at 3,275 miles (5,270 km). If it were orbiting the sun instead of Jupiter, Ganymede would easily be considered a planet. Pluto, demoted to dwarf planet status in 2006, spans just 1,430 miles (2,302 km).

Despite Mercury’s diminutive dimensions, its self-gravity easily crushed it into a sphere long ago. That plus the fact that it revolves around the sun and has cleared its orbit of competition from other smaller bodies places it firmly within the realm of the planets.

And there’s no planet quite like it. Mercury hovers near the sun too close to see and a few weeks later leaps into the morning sky. Drifts back down toward the sun in a few weeks and then leaps into the evening sky. So it goes, back and forth like that a half dozen times a year. Northern hemisphere observers see it best at dusk during late winter and spring ‘elongations’ and at dawn in the fall.

It’s easy to guess the reason for its swift maneuvering – a tight orbit around the sun lasting only 88 days keeps Mercury on the move.

Mercury looks like a tiny gibbous moon this week through a small telescope. Use at least 75x to make out its shape.  Illustration: Bob King

Like Venus and the moon, Mercury shows phases. Right now, if you’re lucky enough to train a telescope on it before it atmospheric turbulence near the horizon mushes up the view, the planet would look like a very tiny gibbous moon 66% illuminated.

Its phase changes quickly too. Within a few weeks, as it moves closer to Earth and grows in apparent size, the planet will morph from gibbous to half to a dim crescent. Yes, dim! Mercury is brightest when at ‘full moon’ phase, being nearly as brilliant as Sirius, but fades to 3rd magnitude when a thin crescent. This week we’ll see it brightest; next week the planet will start to fade noticeably.

Orbiting between 28 and 43 million miles (46 and 70 million km) from the sun and possessing no atmosphere, Mercury’s temperature ranges from an extremely hot 800 F (430 C) on the dayside to marrow-chilling -280 F (-170 C) on the nightside.

To the eye, Mercury would appear as shades of dark brown. NASA enhanced the subtle colors to in this photo of the planet, a mosaic of images taken by MESSENGER. Younger craters with their bright rays appear blue. Plains formed form ancient lava eruptions are tan or orange. Credit: NASA

Because the planet’s axis is tilted only .01 degree – it essentially rotates straight up and down perpendicular to the sun – sunlight never reaches into craters in its polar regions. Locked in permanent shadow, NASA’s MESSENGER spacecraft has found strong evidence for abundant water ice and other volatile materials stored there for millions of years.

We could go on and on about this strange little planet, but I’d be holding you back from getting outside to see it for yourself. For more information, check out NASA’s quick-facts summary and a wonderful gallery of photos from MESSENGER.

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.