Monthly Archives: May 2011

How to listen to the aurora borealis

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Laboratory tests reveal that a surprising variety of substances, including frizzy hair and vegetable matter, can act as radio-to-audio VLF transducers. Credit: NASA

I wasn’t just watching this weekend’s aurora display but listening to it, too. No, I didn’t hear the ‘swishing’ or ‘crackling’ reported by some. Despite seeing hundreds of displays ranging from meek to wild, I’ve yet to actually hear any auroral audio. There is some evidence however that electrophonic transduction can convert otherwise very low frequency (VLF) radio waves given off by the aurora into sound waves through conductors. Wire eyeglass frames, grass and even hair can act as transducers to convert radio energy into low-frequency electric currents that can vibrate an object into producing sound. Similar ‘fizzing’ sounds have been recorded by meteor watchers that may happen by the same process.

The WR-3 VLF receiver with headphones. Photo: Bob King

Of course another reason people might hear auroras is they imagine a soundtrack. It’s a psychological thing – you see a spectacular display of auroral light and in your head hear sounds your imagination might expect like crackling and whooshing. Given that the aurora is never closer to the ground than 50 miles, the air is far too thin to transmit any weak sound waves that might be produced to your ears.

If you’re like me and hard of auroral hearing, a small VLF radio receiver will do the job nicely. This handheld device converts very low frequency radio waves produced from the interaction of the solar electrons and protons with the Earth’s magnetic field into sounds you can listen to with a pair of headphones.

We’re used to waves of light which are very, very short, measuring in the millionths of an inch long. The pigments in our retinas convert these waves into visible images of the world around us. Radio waves given off by auroras and other forms of natural ‘Earth energy’ like lightning range from 19 to 1,800 miles long or longer! To make them available to our senses we use a radio receiver. I fire up a little unit called a WR-3 that I bought for $60 back in the mid-1990s. The components are housed in a small metal box with a whip antenna and powered by a 9-volt battery. The on-off switch also controls the volume. Plug in a set of headphones and you’re ready to listen. That’s all there is to it.

A rural location is ideal for listening to the subtle sounds of the aurora with a VLF radio. Just turn it on and hold it up to the sky.This photo was taken early Saturday morning when green auroras were still visible through breaks in the clouds. Photo: Bob King

The receiver picks up lots of things besides aurora including a big ‘unnatural’ hum from alternating or AC current in power lines and home appliances. It creates a loud, continuous buzz in the headphones. You’ll need to be at least a quarter mile from any of those sources in order to hear the more subtle music of the planet. I drive out to a open ‘radio quiet’ rural area, turn on the switch and raise the antenna to the sky. Don’t stand under any trees either. They’re great absorbers of the low frequency radio energy you’re trying to detect.

The magnetosphere of the Earth is enormous bubble of magnetism that surrounds our planet. It's created through the interaction of the solar wind and Earth's magnetic field. The magnetosphere acts as a shield to protect us from dangerous radiation in space. Credit: NASA

The first thing you hear will be the pops, crackles and sizzles of distant lightning called sferics which are similar to what you’ve probably heard on your car radio during a thunderstorm.

Lightning gives off lots of energy in the long end of the radio spectrum. When that energy gets ducted through the upper layers of Earth’s atmosphere called the ionosphere over distances of several thousand miles, it emits another type of sound called ‘tweeks‘ which remind a listener of pings or dripping water. Flurries of tweeks have an almost musical quality like someone plucking the strings of a piano.

Lightning produces a great variety of radio 'sounds' you can hear with the right receiver. Credit: Mircea Madau

When those same lightning radio waves enter Earth’s magnetosphere and interact with the particles there, they can cycle back and forth between the poles traveling tens of thousands of miles to create what are called whistlers. These things sound really eerie. After their long journey, the higher frequency waves arrive before the lower frequency ones causing them to spread out in tone. What you hear are a series of descending whistles that remind me of the whistling sound of bombs released from a plane like you’d see in a World War II movie. Tweeks are very brief; whistlers last anywhere from 1/2 to 4 seconds or longer.

Sometimes you’ll hear dozens of whistlers one after the other. There there’s the aurora. When conditions are right, a VLF receiver can pick up disturbances in Earth’s magnetic bubble spawned by auroras called ‘chorus‘ or ‘dawn chorus’. Talk about strange. Sometimes there are swooshing sounds, but chorus primarily sounds like a pond full of peeping frogs or a flock of birds singing at sunrise. Click on the links above to hear the different sounds.

An active auroral display sounds like a chorus of chirping birds through a VLF radio. Photo: Bob King

Saturday night was a bonanza for natural radio. I heard all the phenomena described above. A line of passing thunderstorms provided a bounty of crackles and tweeks early on. As they thunderheads drifted far to the east, whistlers were heard a couple seconds after the appearance of every distant lightning flash. Most of these lasted 3 to 4 seconds, meaning they’d traveled back and forth between Earth’s magnetic poles. How astonishing it was to sense our planet’s magnetosphere through sound.

When the aurora was strongest starting around 1 a.m., the chorus rose from the background noise of lightning sferics and burbled and chirped along for nearly an hour. Later, through the aurora was still active, the sounds mysteriously disappeared.

I realize this radio stuff may not be everyone’s piece of pie, but if you’re interested in listening to VLF and in particular the aurora, basic receivers are available through at least several online sites shown below. I’ve only used the WR-3 and can’t speak for the others, but they all run around $125. Oh, and by the way, don’t use one when there’s a lightning storm nearby. Holding a metal aerial under a thundercloud is not recommended!

* The INSPIRE Project
* WR-3 VLF receiver from Stephen McGreevy
* North Country Radio ELF Earth Receiver

More on natural radio can be found HERE. Things to keep in mind when considering a purchase are whether you have access to an open area 1/2 mile from a power line and away from homes. You’ll also need patience. Many nights you’ll only hear lightning crackles from distant storms thousands of miles away peppered by the occasional ping of a tweet. Whistlers may not appear for weeks at a time and then one night, you’ll hear them by the hundreds. But if you regularly watch the sky, it’s so easy to take the radio along and ‘give a listen’ for some of the most curious sounds you’ll ever hear. It’s just one more way to be in touch with the home planet.

Join me for a roller coaster ride aboard Endeavour

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A video camera on the exterior of the International Space Station captured this image of space shuttle Endeavour a little less than an hour after the two spacecraft undocked. Photo credit: NASA TV

Don’t miss the Double Flyby! Late last night, after the space shuttle Endeavour undocked from the International Space Station (ISS), pilot Greg Johnson flew the craft in a circle around the station so the astronauts could take still and video pictures of it. Commander Mark Kelly then took the controls for a test of an automated rendezvous and docking system.

Tomorrow morning you’ll see one following the other as they take the same path across the dawn sky. For the Duluth, Minn. region, the Double Flyby – a brilliant one – begins at 4:10 a.m. when the pair first appears in the southwest moving east. They’ll glide through the constellation Aquila and Great Square of Pegasus, and cruise just above the planet Jupiter before “setting” in the east.  I don’t know yet which which craft will be leading and how far ahead of the other it will be, but the ISS is typically brighter than the shuttle. To ensure you see them both, start looking a few minutes early.

Since the shuttle will land at 1:35 a.m. Central Daylight time on June 1, this will be the last opportunity to see the two in tandem. I’m hoping our forecast for partly cloudy skies tonight holds true. This is one to set the alarm for.


Endeavour’s launch from booster cameras

Whether your skies are cloudy or clear, you don’t want to miss seeing this amazing video that shows the May 16 launch of Endeavour from the perspective of cameras mounted on its booster rockets. You’ll really feel like you’re on a roller coaster of a ride as you watch the liftoff from four different angles. I don’t know if this is the first time NASA has released these videos publicly, but it’s my first viewing.

A few things to watch and listen for are the darkening of the sky from blue to black with increasing altitude, the exhaust plume and its shadow visible back down on Earth, the drop in loudness of the burning fuel as the air thins out, the gradual increase in sound volume as the boosters fall back through the atmosphere and the final in-your-face ocean splashdown. You’ll find plenty of other interesting things going on as well. Be sure to punch the video up to full screen for maximum enjoyment.

Can you still spot the bright star Capella in the northwestern sky during evening twilight? This map shows the sky about 75 minutes after sunset. Created with Stellarium

When the shadows are deepening and twilight pink lingers in the west, Capella still twinkles brightly. This star, which is located in the northern constellation Auriga the Charioteer, is visible year-round for the northern U.S. and Canada, reaching its lowest point above the northern horizon around 2 a.m. in early June before resuming its climb in the east.

Capella looks a little lonely way down there, but being the 6th brightest star in the sky (magnitude 0.0), it still catches your eye. Because of its low altitude, Capella is typically aflutter with air turbulence, which causes its pinpoint image to shift this way and that making the star twinkle.

We look through a greater thickness of moving, turbulent air when our gaze is directed near the horizon. That's why stars twinkle more strongly there than overhead. Illustration: Bob King

If you notice it sputtering like a sparkler, take your binoculars out for a closer look. That way you’ll better see it twinkling in every color of the rainbow, flashing red to orange to blue as the varied air acts like a lens, refracting Capella like a prism into evanescent sparks of colored light.

Sleep deprivation by northern lights

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This is the isolated patch of aurora described in the text below. It's unusual because it wasn't connected with any other visible display. Details: 18mm lens at f/2.8, ISO 3200 and 30-second exposure. Photo: Bob King

As long as you don’t have too many commitments the next day, losing sleep over the aurora is hardly a painful thing to do. If you know you’ll need to function at a high level the following morning, you waste energy worrying about how late it’s getting and the need to turn in early. But if your only responsibility is to dump bags of wood chips on a garden path, you can get by on a few hours of sleep without a care.

Between about 1 and 3 a.m. this morning, the aurora developed into multiple low arcs and a few diffuse rays and curtains across the northern sky. Details: 24mm lens at f/2.8, ISO 1600 and 30-second exposure. Photo: Bob King

That’s why I felt free to chase the northern lights till 3 a.m.  The NOAA Space Weather forecast called for the possibility of “minor storming” last night from particles streaming toward Earth from a gaping hole in the sun’s corona. I drove north out town with telescope and camera. An eerie sight greeted my eyes as soon as I got out of the car and looked north. Here was an oval patch about the size of a fist at arm’s length below the North Star. It slowed pulsated from faint to brighter and back again like some kind of ponderous whale heart. I quickly took several pictures in what turned out to be just five minutes of clear sky. Fog and clouds soon claimed the stars and quenched the mystery aurora.

A plot of the auroral oval at 1:05 a.m. Central time using data from the Polar Operational Environmental Satellite (POES). The oval, which shows the extent of the aurora, sags far enough southward to appear in the northern sky from Duluth, Minn. and many other locations in the upper Midwest. Credit: NOAA

Later I drove along a variety of asphalt and gravel roads in search of better skies. Around 1:30 the clouds departed and the aurora had all the room it needed to dance and stretch across the northern sky. The display featured a low, bright greenish arc and pale diffuse rays and patches reaching to the Bowl of the Big Dipper. The pieces and parts moved with slow and deliberate ease like someone practicing meditative yoga. And watching it was exactly that – a form of meditation.

More aurora is forecast for tonight for the higher latitudes, ie. the northern U.S., Scandinavia and Canada. Many of us in the U.S. will have tomorrow – Memorial Day – off from work. Guess what I’m thinking?

Astronomy apps for iPhones and iPads

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** Aurora alert: The northern lights were seen last night from high latitudes, and there’s a good possibility they’ll return tonight. If you live in the northern U.S. and Canada, keep a lookout to the north after nightfall for activity. **

SkyView lets you find the planets in the sky anywhere and anytime.

Sooner or later I’ll end up owning an iPhone or iPad. I thought the use of “two fists to the right of the moon” to find a star or planet wouldn’t be necessary when green lasers became commonplace. Pointing the Star Wars-like beam from one celestial object to the next eliminated the need to stretch a fist to the sky. Now that’s just so passé! It’s been superseded by – what else? – the mobile phone.

Some of the new astro apps astound with their ease of use, data and beautiful graphics. One of them, SkyView, was brought to my attention by a friend, who was amazed when his friend pointed his iPhone at the floor and said: “There’s Pluto.” With SkyView you can find any planet anytime no matter where it is. When not directly visible in the night sky, your screen will show it superimposed on whatever’s in the way, be it a building, the ground or your mother telling you to get out of the house and find a job. Sort of like having X-ray vision.

This frame grab shows the constellation Aries - and its mythological figure - along with altitude, azimuth and other data.

That’s not all. The app shows when and where the sun and moon rise and set – ideal for planning photos at those special times – and helps you find stars and constellations in the sky using “augmented reality” graphics. Need to confirm that bright star is Vega? Point the phone and find out. It even has the ability to track satellites like the space station and shuttle, turn itself into a scientific instrument with data readout on your location, compass directions, etc. and displays information about the object of interest.

Get this app for $0.99 and you’ll never read this blog again. There’s even a free version available. It’s compatible with iPhone 3GS, iPhone 4, iPod touch (4th generation), iPad 2 Wi-Fi, and iPad 2 Wi-Fi + 3G. Another similar and very popular app is Star Walk from iTunes for $2.99.

Zoom out to Saturn and get a unique perspective on its rings and moons with Grand Tour 3-D

Other excellent astronomy programs for mobile phones include the Galaxy Collider, which lets you see what happens when galaxies collide in space. Great for those of us who feel like we have no control over our lives. Consider it a preview for when the Andromeda Galaxy and Milky Way smash into each other several billion years from now. Or take the Grand Tour 3D, an app that lets you visit each of the planets and their moons. Very pretty graphics. And don’t forget Moon Globe if you’re like me and enjoy virtual trekking across the lunar landscape through hi-res photography.

 

I could go on and on with the list of apps, but instead I’ll let you check out this fellow’s 15 Astronomy Apps for iPhone and Dan Schroeder’s Star Charting apps. Here are more astronomy apps for Windows phones and Pocket PCs. And if you have suggestions for favorite programs, please pass them along by clicking on the Comments link. Thanks!

Saturn's rings are seen edge on in this photo taken by Cassini in January 2011. Five of Saturn's moons are visible in the image. See text below for their identities. Credit: NASA/JPL/Space Science Institute

As much as I like my reality augmented, it’s nice to look at real photographs taken by cameras. I came across this wonderful image of five of Saturn’s moons taken earlier this year by the Cassini spacecraft in orbit about the planet. Rhea at 949 miles in diameter is the largest and closest in the picture, while Dione (698 miles) looks like it’s almost sitting on the rings near the center. Itty bitty Prometheus (53 miles) is barely visible buried in the rings to the right of Dione. Epimetheus (70 miles) lies to the right of the rings and Tethys (660 miles) at far right.

Endeavour and ISS join the moon and Jupiter at dawn

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Ouch! The Soyuz TMA-20 spacecraft, carrying astronauts Cady Coleman, Paolo Nespoli and Dmitry Kondratyev, lands in a remote area in the steppes of Kazakhstan earlier this week. Photo credit: NASA/Bill Ingalls

Morning sky watchers, do we have something for you. The International Space Station (ISS) with space shuttle Endeavour in tow is once again making passes over North America at dawn. Since the shuttle will return to Earth during the early morning of June 1, we’ll hopefully get to see them separate and chase each other around the sky for a time before the landing.

Even better, a beautiful crescent moon will be buzzing the morning planets during the same time.  Tomorrow morning (Saturday) the moon will be about a fist to the upper right of Jupiter, but on Sunday they’ll be twice as close and rise together. The best time to see them is about 45 minutes to an hour before sunrise. Look very low in the eastern sky. Then on Monday morning a very thin lunar crescent will lie near the planets Mars and Venus. I’ll provide a map in Sunday’s blog to point you in the right direction.

This map shows the moon and the planet Jupiter about an hour before sunrise this weekend. Created with Stellarium

The times listed below for ISS/Endeavour viewing are Central Daylight and accurate for the Duluth, Minn. region. For times for your town, go to Spaceweather’s Satellite Flyby site and type in your zipcode or login in to Heavens Above and click on the ISS link. At the latter site, clicking on the date will bring up a map showing the space station’s path across your sky.

The space station/shuttle moves from west to east across the sky and appears like a bright, nearly-steady light. I say nearly because sometimes the ISS can flare to greater brightness for seconds at a time.

* Saturday May 28 starting at 4:35 a.m. The ISS will follow a low arc across the south and southeast. It passes very close to Jupiter near the end of its viewing path.
* Sunday May 29 at 4:58 a.m. Much brighter and higher pass in the south! Watch it cruise just a couple degrees above the crescent moon around 5:02 a.m.
* Monday May 30 at 3:47 a.m. Low pass in the southeastern sky
* Tuesday May 31 at 4:09 a.m. Fine, bright pass across the south.
* Wednesday June 1 at 4:31 a.m. across the top of the sky. Brilliant pass! Last one with the shuttle Endeavour before it lands.
* Thursday June 2 at 3:22 a.m. across the south-southeast and a second pass across the northern sky at 4:55 a.m.
* Friday June 3 at 3:43 a.m. Brilliant pass across the top of the sky!

Finally, according to NOAA space weather forecasters, there’s a chance for aurora at higher latitudes from May 27-29. Wouldn’t it be awesome to see the shuttle/ISS, moon and Jupiter with a dash of northern lights?

Warm nights coax out Scorpius the scorpion

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These maps show sky facing southeast shortly after nightfall around 10:30 p.m. Scorpius' brightest star, Antares, translates as 'anti-Ares' or 'rival of Mars' because of similarity in color and brightness. M4 is a globular cluster easily found in a typical pair of 10x50 or 7x50 binoculars. Look for a fuzzy patch. Created with Stellarium

If I had to pick one constellation indelibly associated with the month of May it would be Scorpius the Scorpion. We could have chosen Virgo or Bootes, which stand high in the south and call for our attention with both eye and telescope. But there’s something about Scorpius crawling up from the southeast with its twinkly red star Antares (An-TAIR-eez) that stirs me almost as much as the return of spring flowers.

 

You'll need to stay up until 1:30 a.m. to see the full outline of the scorpion in May. The bottom of the tail is cut off by the southern horizon from my location in Duluth, Minn., except for the tip, marked by the star Shaula, an Arabic word for 'stinger'.

You wouldn’t think a scorpion would have that effect on the psyche, but it does on me. While you may not necessarily pay attention to the mythology behind them, constellations will always be associated with happenings here on Earth. Each has its own season of visibility; for northern hemisphere viewers, Scorpius’ appearance means we’ve transitioned from a wintry world into a green one. Antares’ ruddy light hints at the sun’s warming rays.

Seeing the head of the Scorpius in late May also reminds us that the summer Milky Way isn’t far behind. There’s no sight more magnificent than that waterfall of starlight rising up from the northeast and cascading its way through the zenith before crashing into a foaming frenzy near the southern horizon. We’ll visit again with Scorpius and  his minions in the coming weeks.

The International Space Station with the docked space shuttle Endeavour is seen from the Soyuz TMA-20 spacecraft. Photo credit: NASA TV

We’re so used to seeing our photos immediately after they’re taken – just press the replay button and BINGO we got ‘em. That makes it hard to accept the delay in seeing the historic pictures of the space shuttle Endeavour docked with the International Space Station taken Monday by the departing astronaut crew. Yes, Monday, literally an eon ago in digital years. The cards containing the images were left in the Soyuz capsule after the astronauts landed. Today (Thursday) they’ll be shipped to Moscow and processed as per standard procedures. NASA should get the images sometime next week. In the meantime, this low-res frame grab from NASA-TV taken from Soyuz  hints at what’s to come.


The OSIRIS-REx mission will arrive at asteroid 1999 RQ36 in 2020, study and photograph it, then reach out to gather a sample that will later be returned to Earth.

In other space news, NASA announced it will launch the OSIRIS-REx (Origins-Spectral Interpretation-Resource Identification-Security-Regolith Explorer) probe to near-Earth asteroid 1999 RQ36 in 2016. When it arrives at the asteroid 4 years later, the craft will extend a robotic arm to grab a sample of rock and dust from its surface, place the contents in a small capsule and launch the capsule back to Earth. The approximately two ounces of RQ 36 ‘dirt’ arrives back home for study in 2023. This will be the first U.S. mission to return an asteroid sample. Scientists hope to learn more about the composition of asteroids, which are composed of the first solid materials formed in the early solar system. Read more about the mission HERE.

Spring’s newest ‘double-double’ star

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Saturn (left) and its 'companion' Porrima make a lovely naked eye "double star" during May and June. Details: 35mm lens at f/2.8, ISO 1600 and 20-second exposure. Photo: Bob King

We’ve got a new double star in the spring sky! OK, it’s only a made-up one and temporary at that, but Saturn and the star Gamma Virginis, also known as Porrima, make one of the most realistic close pairs of ‘stars’ I’ve ever seen. Their resemblance to a telescopic view of a true double star is remarkable.

Face due south at nightfall and look about halfway up to find Spica and Saturn. Less than 1/2 degree to the planet’s upper right is Porrima, named after a Roman goddess of prophecy. At magnitude 3.5, the star is considerably fainter than the planet, but its nearness makes it quite easy to see. The star stays put, but Saturn, being a planet, continues to move in Porrima’s direction until June 9. That’s when they’ll be closest at just 1/4 degree apart. Of course Saturn is very much in the foreground at a distance of 836 million miles (1.25 light hours) compared to Gamma’s 39 light years.

After that date, Saturn will appear to reverse direction and begin tracking back to the east. Their separation will increase and the thrill will be gone.

The double star Porrima photographed in 2003 when the two were closer together than they are now. Credit: Damian Peach

The beauty of this close pairing is that Porrima itself is a true binary or double star, making its proximity to Saturn a ‘double double’ delight. It’s also one of the few binaries whose companions amateur astronomers can watch move over the course of a few years.

The two stars are similar to the sun but hotter and nearly identical in size. They go around each other every 169 years in an elliptical orbit that cyclically brings them closer together and farther apart as seen from Earth. Closest approach was in 2005 when the duo was separated by the same distance Jupiter is from the sun or about 500 million miles. When farthest apart around the year 2080, they’ll be twice Pluto’s distance from each other. Check out this orbital diagram to get a clearer picture of what I mean.

Planets that are closer to the sun move faster than those that are in more distant orbits. The same is true with double stars. Porrima’s two stars are still moving relatively quickly since closest approach 6 years ago, making it possible for amateurs equipped with a modest telescope (4-inch and larger) to watch them separate and change position relative to one another in just a few years time.

Saturn is almost due south at nightfall in late May. It forms a triangle of bright stars with Spica and Arcturus. Created with Stellarium

As of this spring, the two are separated by a gap of just 1.7″ of arc. That’s pretty tiny. Remember that a second of arc is equal to 1/60 of a minute or 1/3600 of a degree. For reference, the full moon is 1/2 degree or 30 minutes of arc in diameter.

The slightly fainter companion lies to the northeast of the brighter ‘primary’ star. Use high power to split the pair and make a sketch. While the difference in position won’t be obvious in a year, six or seven years from now, the companion will be considerably farther away and due north of the primary star. Dust off that old sketch, compare the view and you’ll see that the stars have move of their own motion in just a few short years.

Alien planets for May nights

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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

C. Marois et al., NRC Canada

Unique shuttle-space station photo planned tonight

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This photo, taken on Sept. 10, 1991, of Superior Fire Department Capt. Leonard Rouse giving mouth-to-mouth resuscitation to a kitten. The kitten survived and was adopted by Rouse, who named it "Smudge". Credit: Charles Curtis, Duluth News-Tribune

I worked for many years with photographer Chuck Curtis at the Duluth News Tribune. He’s since passed away. Besides the daily run of photo assignments, Chuck would come up with occasional photo ideas of his own that he’d carefully plan out in advance for just the right angle and effect. I remember one in particular of an ice fisherman on Lake Superior taken from a great distance with a long telephoto lens at sunrise. He noted the sunrise point and the chose the best location from which to shoot in advance to capture the cold, colorful scene.

Early this evening, a Soyuz spacecraft piloted by Russian cosmonaut Dmitry Kondratyev and carrying NASA astronaut Cady Coleman and an Italian astronaut Paolo Nespoli will undock from the International Space Station and back away to a distance of about 650 feet. Instead of departing immediately to return to Earth, the spacecraft will pause, allowing time for Nespoli to seat himself at a window to take still photos and video of the shuttle-space station- Russia/European cargo ship complex. Once he’s in position, the space station will be rotated through 130 degrees to show off the shuttle Endeavour to best advantage.

 A NASA simulation shows different views of how the shuttle Endeavour and International Space Station will appear this evening, when a the crew of a Russian Soyuz capsule photographs the complex after undocking. Credit: NASA TV

Sounds easy enough, but the unique opportunity to photograph all the international partners involved in the space station complex took plenty of work and cooperation with the Russian space agency Roscosmos responsible for the Soyuz craft. They originally nixed the idea because of technical reasons involved in the special maneuver, but because Endeavour’s launch was delayed two weeks, that put the shuttle at the station at the same time as the planned Soyuz return to Earth. Taking photos during the departure would almost be a no-brainer.

Once the Soyuz crew is on the ground, NASA and Roscosmos will release the pictures as soon as possible, perhaps even by tomorrow. It will be the first photo of a shuttle and the space station against the backdrop of Earth taken from a remote vantage point. If Chuck were still here, he’d be smiling in appreciation of such a well-planned photo op.

North is up in this photo taken on May 21 of Jupiter. The narrower, dark belt is the NEB; the broader, paler belt is the SEB. The dark spots are the shadows of the moons Io (left) and Europa. Credit: Christopher Go

As we’ve seen in recent blogs, Jupiter is returning to view in the morning sky in the constellation Pisces the Fish. You’ll find it very low due east some 30-45 minutes before sunrise. Of the four planets currently visible at dawn, it’s the easiest to spot. Recent photos taken by Philippine amateur astronomer and astrophotographer Christopher Go reveal that Jupiter’s South Equatorial Belt (SEB), famous for disappearing more than a year ago, has fully revived and easy to see in even small telescopes. The North Equatorial Belt (NEB) is very dark and red in color. What surprises will the planet have in store for us this season?

Bootes – the constellation nobody can say right

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Bootes the Herdsman is well placed for viewing during early evening hours in late May. He keeps two dogs which represent the neighboring constellation Canes Venatici. Credit: Urania’s Mirror

Some constellation names are easy to pronounce at first sight like Leo, Hydra and Cygnus but then there’s Bootes. On first encountering the word as a young teen, I still remember calling it ‘booties’. That’s what it looks like after all. ‘Boots’ is another variation I’ve heard many times since. And yet somehow you know the ancients wouldn’t have created a cultural myth based on a pair of galoshes.

It’s really pronounced ‘Boe-OH-teez’ and represents a herdsman. The word’s origin isn’t certain but it may come from the Greek word for ‘noisy’ and refer to the herdman’s shouts to his animals. Or it might be rooted in the ancient Greek word for ‘ox driver’. The nearby constellation of Ursa Major (the Great Bear) was sometimes depicted as a cart pulled by oxen.

The cone-shaped constellation Bootes extends north of the bright star Arcturus, an orange giant star 37 light years from Earth. This map shows the sky facing south around 10 p.m. in late May. Maps created with Stellarium

In the 21st century I’ll often refer to it as the ‘ice cream cone constellation’ because Bootes’ outline resembles a sugar cone topped by a single scoop. Whatever it is, it’s not hard to see, because the group contains the fourth brightest star in the sky, Arcturus.

Face south at nightfall and you’ll see two bright ‘stars’ halfway up in the southern sky. Those are Saturn and Spica and they’re separated by one fist held at arm’s length. Now tip your head back and gaze off high and to their left to spy a  brilliant orange-pink star. That’s Arcturus, a Greek word for ‘bear guard’. If you’re crazy enough to tip your head even further back and risk falling over, you’ll understand the name’s origin. Arcturus follows the Big Dipper, part of the Great Bear, which is nearly overhead.

Arcturus forms a large, temporary figure in the late spring-early summer sky sometimes referred to as the Spring Triangle. The ice cream cone part of Bootes is composed of a handful of stars extending two fists to the north or above Arcturus. Two little ‘antennae’ poke out on either side of the brilliant star to complete the constellation’s outline. That wasn’t too hard, was it?

 

M3 forms a right triangle with Arcturus and the star Eta or a nice equilateral triangle with Arcturus and Rho. The cluster is about two binocular fields of view away from Arcturus. Both M3 and the marked star are 6th magnitude. Stars are shown to magnitude 7.5.

Next we’ll use your new-found knowledge of Bootes to visit one of spring’s most outstanding star clusters, the globular cluster M3 in nearby Canes Venatici. For this you’ll need a pair of binoculars – even small ones will do. Once your eyes are adapted to the darkness, point your binoculars at Arcturus and the fainter star Eta Bootis to its right. The cluster is about two binocular fields of view directly above Eta and forms a right triangle with Eta and Arcturus.

M3 will look like a bright, ‘fuzzy’ star right next to a similarly-bright but real star. It’s most convenient the two are next door to each other because the star helps us tell the two apart.

M3 shows its true colors as one the sky’s finest globular star clusters in this photo made with a 32″ telescope. It’s 33,900 light years away and 180 light years across. Globular clusters are rich, spherical collections of stars in the outer halo of our Milky Way galaxy that revolve around the galaxy’s core. Credit: Jim Misti

“Magnificent” will probably not be the first word to pop out of your mouth upon seeing M3, but we are using binoculars after all. In truth, there are a half million stars packed into that tiny undistinguished spot. To get a sense of this cluster’s true beauty, a modest 6-inch telescope and dark skies are required. They you’ll begin to tease out dozens upon dozens of tiny stellar points winking like fireflies around M3′s radiant core. Larger scopes provide a most impressive view that will keep an observer glued to the eyepiece for many minutes.

M3 was discovered by Charles Messier on May 3, 1764 and added to his catalog – the Messier catalog – of fuzzy objects not to be confused with his favorite quarry, comets.

There are two main types of clusters in our sky – the wider, spread-out variety like the Seven Sisters (Pleiades) called open clusters and the densely-packed, spherical globular clusters. Open clusters populate the Milky Way’s spiral arms and are generally much younger than the globulars, which occupy a great halo of space around the center of galaxy. They’re the mighty ancients of the universe with ages of 10 to 12 billion years. In contrast, most open clusters break apart into individual stars after several 100 million years.

When you look at M3, whether by telescope or binoculars, it’s hard to imagine its size and star density. 500,000 stars gathered into a sphere that spans five times the distance between Earth and the star Arcturus. Just think of that. What human imagination could have ever conceived of the wonder that nature rolls out with casual ease on warm May evenings.