The head of Scorpius the Scorpion with its bright star Antares reachest its highest altitude in the southern sky this time of year. It’s ideally placed for viewing at the end of evening twilight a little more than two outstretched fists above the southern horizon. Details: 35mm f/2.8, ISO 800 and 20 second exposure. Photo: Bob King

Most of us don’t have ideal skies. We live with light pollution and views of the celestial sphere that are compromised by trees and buildings. I know how good it feels when every so often I drive out to a treeless, open place and experience the starry sky all around me. It’s positively liberating when the barriers to the cosmos are removed. But most of the time I’m like you and have to contend with missing pieces of the sky. One piece missing from my neighborhood is the bottom 20 degrees of the southern sky, which prevents a complete view of one of the coolest of the 88 constellations, Scorpius the Scorpion. Cool because it’s one of the few that really resembles its name.

The view of Scorpius is compromised for observers in the northern U.S. but not by much. If you do have access to an observing spot with an open horizon to the south, you’ll be able to see all the way down to Shaula, also called the "Stinger" star in the scorpion’s tail. Maps created with Stellarium

Scorpius never rises very high for sky watchers at mid-northern latitudes, so I’m going to guess many of you are in the same situation as I am. From my home, only the head of the Scorpion clears the trees on June and July evenings. Much of the tail is hidden by branches and leaves, while the very bottom of the constellation scrapes the horizon. We northerners content ourselves just the same with the pleasures of red Antares, the scorpion’s brightest star, and the three-stars-in-a-row that form the head, a summertime version of Orion’s famous Belt.

As Donald Trump might say, Antares is "YOOGE!". While cooler than the sun, it more than makes up for its dimmer surface by sheer size. That’s the reason it shines brightly despite its considerable distance of 600 light years. In the diagram, R stands for radius which is equal to 1/2 the diameter.

In contrast to the tiny stars we’ve been examining over the last week, Antares is a red supergiant 800 times the diameter of the sun. Its expansive girth would fill the solar system beyond the orbit of Mars if it plopped in place of the sun. The Mars connection is an apt one, since the name Antares comes from the ancient Greek "anti" and "Ares" or Rival of Mars, referring to its color which is nearly identical to the planet.

Traveling this summer? If you’re headed south or if you live in the  southern U.S. , you’ll have better luck than us northerners at seeing the complete scorpion. For every degree of latitude you drive or fly south, the stars in the southern sky rise higher by an equal amount. One degree is equal to two full moons side by side.

Sky watchers in the central and southern U.S. might be more familiar with the whole scorpion. As you travel south of my town along the curvature of the Earth, the stars in the southern sky rise ever higher while those in the north drop closer to the northern horizon. By the time you’ve reached Denver’s latitude of 40 degrees north, Scorpius’ tail easily clears the horizon. Continue to New Orleans and it literally sails across the sky. There are many deep sky treats in Scorpius for both binocular and telescope users, not to mention the Milky Way is magnificent there when seen from a dark sky. Tomorrow we’ll drop in on a few of these beauties.

The Seven Dwarfs in the famous "Heigh ho" sequence in Walt Disney’s Snow White and the Seven Dwarfs. animated by Shamus Culhane. Credit: Walt Disney/RKO Pictures

"Heigh-ho, heigh-ho, it’s home from work we go!" Who doesn’t recall
the seven Disney dwarfs breaking into song after digging all day in
the mines in Snow White and the Seven Dwarfs. My favorites were Happy
and Dopey, which probably says a lot about my personality, but my wife
would cast me as Grumpy in a second. Dwarfs pop up in astronomy, too.
The other day we looked at red dwarfs, those small stars that populate the
galaxy in the billions. There are more of these humble stellar fires than all the
giant and supergiant stars thrown together.

Recall that red dwarfs contain a lot more matter than Jupiter but are
only a couple times its size. They’ve enough kindling in the form of
hydrogen gas and sufficient pressure in their cores for nuclear fusion
to occur. Once a star begins fusing hydrogen, it releases prodigious
amounts of energy, literally becoming a sphere of fiery gas. The only
thing keeping it from blowing apart is the counteracting pressure of
gravity.

This comparison diagram gives you a good idea of how brown dwarfs stack up against the sun and planets. Brown dwarfs range between about 13 and 80 times the mass of Jupiter. Below that we enter the realm of planets while above it are the true stars. Credit: Jon Lomberg/Gemini Observatory

Planets never get hot enough to "burn" hydrogen and therefore don’t
radiate light of their own. Some may be the right size, but
the matter in their interiors is simply not dense (or hot) enough for
fusion to take hold. Planets shine by "borrowed" light from their host star which
they reflect back into space.

Red dwarfs are true stars, but their brown dwarf cousins are not.
Brown dwarfs fall somewhere between giant planets like Jupiter and red
dwarfs in size and temperature. A typical one might pack 45-80
Jupiter’s masses of mostly hydrogen into a sphere about Jupiter’s
size. The least massive of them contain only 13 Jupiter’s worth of
material. One of the most amazing traits of all brown dwarfs whatever their
mass is they’re all about Jupiter’s diameter or some 11 times the size of Earth.

The red object at center is the dim brown dwarf 2MASS 0415–0935. It emits almost no visible light at all and was photographed in the infrared. It has a surface temperature of just 770 degrees Fahrenheit, only a few hundred degrees hotter than your oven. Credit: U.S. Naval Observatory

A hefty brown dwarf briefly burns deuterium (a form
of hydrogen) in its youth, but that internal fire soon peters out, and the star
cools down like an unplugged iron, fading from dull red to black.
The heat they do retain comes from the release of the remaining thermal
energy in their cores. Typical brown dwarf surface temperatures are around
1300 degrees or about the same as an electric stove coil set on high.
Perfect for heating up water for tea.

If that sounds cold for a star, we still have a ways to go before hitting bottom.
The coolest brown dwarfs hardly budge the themometer at just 300+ degrees.
Astronomers have detected methane gas and steamy water vapor in their atmospheres.
These substances couldn’t exist on our blisteringly hot sun, but we do find them
on planets. One thing is clear: brown dwarfs are the bridge between true stars and
the giant gas planets like Jupiter and Saturn.

The first brown dwarf was discovered in 1995 and now hundreds are known.
Most give off little visible light — they’re just too
cool — but they do radiate heat energy or infrared light. A
telescope able to see in infrared will have a much easier task
finding brown dwarfs because they appear brighter than in a typical
telescope. It’s similar to how firefighters use infrared detectors to pinpoint heat
sources that would otherwise be invisible to the eye.

This artist’s concept shows simulated data predicting the hundreds of failed stars, or brown dwarfs, that NASA’s Wide-field Infrared Survey Explorer (WISE) is expected to add to the population of known stars in our solar neighborhood. The green pyramid represents the relatively tiny volume surveyed by NASA’s Spitzer Space Telescope. Credit: AMNH/UCB/NASA/JPL-Caltech

Recently, the Spitzer Space Telescope, an orbiting observatory optimized
for infrared observing, detected 14 of the coldest brown dwarfs ever
discovered. They glow so feebly not a single one is visible in even the largest ordinary
telescope. Their temperatures range from 350 to 620 degrees, which
makes you wonder where we draw the line between planets and stars.

Most brown dwarfs float freely in space and are thought to form like
other stars, from dense clouds of dust and gas that collapsed under the
force of gravity — with one difference. They started out with far less material.
Others formed as companions around larger stars like the pair of brown dwarfs
that orbits the red dwarf star Epsilon Indi.

Spitzer looked at a very tiny slice of sky to spot chilly dwarfs
hundreds of light years away. Based upon that small sample,
scientists believe there are at least a 100 within 25 light years
of the sun. That’s why they expect the WISE (Wide-field Infrared
Survey Explorer) telescope, which can survey chunks of the sky 40
times larger than Spitzer, to ferret out a bevy of browns in the
months to come. These should be close enough for astronomers to employ
the Hubble and other large, ground-based telescopes to tease out a
few more of their dark secrets.

The space station passes very close to the bright star Vega in the constellation Lyra during evening twilight yesterday. Details: 24mm lens at f/4, ISO 200 and 30-second exposure. Photo: Bob King

The International Space Station (ISS) took a swipe at Vega during last night’s 9:56 p.m. pass here in Duluth. It was one of several passes seen that evening and early this morning. You can continue to watch the station every night this week. Here’s a list of times to spot it in the northern Minnesota / NW Wisconsin region. If you’re out of the area, please click HERE for times for your city. The ISS crosses the sky moving from west to east.

* Tonight (June 28) beginning at 10:23 p.m. and again at 11:59 p.m.
* Tues. June 29-30 at 9:14 p.m. and again at 10:50 p.m. and 12:46 a.m.
* Weds. June 30 at 9:41 p.m. and 11:17 p.m.
* Thurs. July 1 at 10:08 p.m. and 11:44 p.m.
* Fri. July 2-3 at 10:35 p.m. and 12:10 a.m.
* Saturday July 3 at 9:26 p.m. and 11:01 p.m.
* Sunday the 4th of July at 9:53 p.m. and 11:28 p.m. The earlier pass happens about the same time most cities set off their fireworks displays. When it appears, tell your friends that bright, moving light is a firework that went into orbit

A line of cumulus clouds lit by the moon inch along the northern horizon last night. Photo: Bob King

I went Comet McNaught-seeking last night but a stubborn line of bulbous cumulus clouds near the northern horizon prevented a view. No problem. The clouds stole the show as they slid eastward, their dark shapes standing in sharp contrast to the pale blue sky and emerging stars. I could just see a faint wash of orange in their towers through binoculars. Judging by how the shadows fell and the lateness of the hour, it was clear that the rising moon was the source of the color. We’ve all seen moonlight clouds, but I don’t ever recall seeing ones colored by a bright, low, orange moon. With the moon still near full, you may want to keep an eye out for the same tonight if you’re "lucky" enough to have a partly cloudy sky.

Check out the conga line of planets in the west the next clear night. This photo was taken at 10:30 p.m., about an hour and 15 minutes after sunset yesterday. Details: 35mm lens at f/2.8, ISO 200 and 12-second exposure. Photo: Bob King

Away in the west, three planets and one bright star dotted the sky in a nearly evenly-spaced line. Tonight their separations will be even more similar. I hope you get to see them.

Cassiopeia and Cepheus begin their rise to dominance in the northeastern sky at nightfall at June’s end. The "W constellation" is about two "fists" above the horizon. Maps created with Stellarium

The king and queen are more than happy to grant an audience to the common sky watcher these late June evenings. I’m referring of course to Queen Cassiopeia and King Cepheus currently holding court in the northeastern sky at twilight’s end. No need for tickets or a "connection". You’re all invited to spend as much time with the royal couple as you like.

Cassiopeia is far better known than Cepheus, because she’s brighter and forms a distinctive W shape that immediately impresses the eye. Her husband takes a little more effort to discern, but with the North Star and the queen herself as your guides, this should not be too difficult. Cepheus traces out a figure, too, one that reminds me of a simple tent or pentagon.

The mythological figures associated with Cassiopeia and Cepheus. Don’t worry about trying to see the outline of a king or queen in their stars. I doubt many of the ancients did either.

Go outside on the next dark night and look low in the northeast around 10:30-11:30 p.m. when dusk is done and night has begun. Make sure you have a reasonably clear view in that direction or else the queen will be hiding among the trees. Once you’ve found the W-shaped Cassiopeia, loft your gaze by one vertically-held fist held at arm’s length above the W. Can you pick out the king’s pentagon? Polaris, the North Star, is a convenient reference just to the left of Cepheus.

The brightest stars in constellations are best known by their proper names like Vega and Betelgeuse. They’re such big sky "personalities" it would just seem wrong to call them by the more generic names of Alpha Lyrae and Alpha Orionis, which refer to each as the alpha or brighest star in their respective constellations of Lyra and Orion. Once we enter the realm of fainter constellations that have no prominent stars, most amateur astronomers default to using stars’ generic names. Maybe it’s because our brains can only remember so many proper names, but it’s more likely these stars simply don’t grab our attention. The convenient Greek-letter cataloging system, Alpha through Omega (brightest to dimmest), serves as a convenient form of shorthand.

Several of the named stars in Cepheus the King and their more generic Greek catalog names.

Cepheus makes a great case in point. The three stars across the top of the constellation — Alpha, Beta and Gamma — form a nice sequence from brightest (Alpha) to dimmest (Gamma). They’re also known by their Arabic names Alderamin, Alfirk and Errai though few put those names to good use. Now that you know them, perhaps you’ll decide to call them by name and raise their status a notch. I daresay doing so may even win you the king’s favor.

What’s this? The right half of the moon is missing — it was engulfed by Earth’s shadow earlier this morning during the partial eclipse. Credit: Andrew Kirk

Our sky was perfect last night … for cloud lovers. I could still tell the moon was out because the road glowed brighter than usual, but that was as close to a clear night as we got here in Duluth. Others were more fortunate, including Andrew Kirk, a regular contributor of photos to this blog. He got up at 3:30 this morning to see and photograph the partial lunar eclipse. What I like about his photo is that moon is eclipsed twice: on the right half by our planet’s shadow and on the left by a mountain peak in the Sierra Nevada range.

Wild strawberries in the backyard photographed moments before they were eaten. Each berry is about 1/3" across. Photo: Bob King

Andrew and the rest of us were treated to the antics of June’s full moon known as the Strawberry Moon. It was named so by numerous Native American tribes after the month’s most ubiquitous fruit, wild strawberries. They’re all over my backyard if I look closely, and while tiny in comparison to the store-bought variety, anyone who’s ever tasted the wild variety will agree they pack a ton of flavor.

Officially, full moon occurred this morning smack in the middle of the eclipse, but as far as our eyes are concerned, the moon will still look nearly perfectly full tonight. You’ll see it rise in Sagittarius and make a very low arc across the southern sky as the hours tick by. The full moon of June is directly opposite the sun, and since the sun is very near its highest point in the sky for the year, that means the moon is at the other end or the lowest place it can be. Indeed the moon sits in the very spot the sun will return to around the first day of winter. Its low path almost guarantees a colorful appearance.

The moon will rise shortly after sunset tonight in the southeastern sky. It’s nearly lined up with the stars Altair and Deneb in the Summer Triangle far above and to the left. Dusty, thicker air in the lower atmosphere gives the moon its characteristic orange color when near the horizon. Created with Stellarium

When our gaze takes us near the horizon we look through much more of the lower atmosphere, which contains lots more dust, water vapor and denser air than higher up where the air is thinner. Shorter wavelengths of light — blues and greens — are scattered or absorbed by the lower atmosphere leaving reds and yellows left to color the moon. Depending on the dust content of the air at your location, so much light can be absorbed, that the moon rises red as … well, a strawberry.

An amazing photo of the aurora australis or "southern lights" from the window of the International Space Station. It was taken on May 29 when modest auroras were also visible in northern Minnesota. Credit: NASA

The combination of the of the International Space Station’s (ISS) inclined orbit around the Earth and the high solstice sun mean the station will remain in continuous sunlight the next few nights. For those of us on the ground that means multiple passes of the space station throughout the night. Satellite watchers refer to these yearly events as ISS Marathons.

How many passes you see on a given night depends on how late you’re willing to stay up. For the Duluth region, Saturday-Sunday is the best night with five passes between 9:30 and 4 a.m. That’s some serious sleep deprivation. Or you could set your alarm and wake up every 95 minutes and then go back to bed. Guess that’s pretty crazy, too. I’ll probably catch the evening ones and leave the a.m. passes for others to harvest.

The ISS always makes its first appearance in the western sky and travels eastward, taking about five minutes to cross the sky. On each pass, the station will be at least as bright as Sirius, the brightest star, and sometimes nearly equal Venus’ brilliance. The times below are for the Duluth and northern Minnesota region. For times for your town, please click HERE and enter your zipcode.

* Friday-Sat. June 25-26:
– 10:39 p.m. High brilliant pass across the southern sky
– 12:14 a.m. Across the northern sky
– 1:50 a.m.  Across the north
– 3:25 a.m. High, brilliant pass across the south

* Sat.-Sun. June 26-27:
– 9:30 p.m. Across the south
– 11:05 p.m. Bright pass across the north
– 12:41 a.m. Across the north
– 2:17 a.m. Bright pass high in the north
– 3:52 a.m. Low across the south

* Sun-Mon June 27-28:
– 9:56 p.m. Brilliant pass across the top of the sky
– 11:32 p.m. Pass across the north
– 1:08 a.m. Pass across the north
– 2:43 a.m. Brilliant pass high in the south

While you’re out, especially Saturday night, be alert for green glows near the northern horizon. A solar wind stream might just connect with Earth’s magnetic field and send a little auroral storm our way. As if an ISS Marathon and potential aurora aren’t enough, those of you reading this who live in the western U.S. and Hawaii will get to see a partial eclipse of the moon early tomorrow (Saturday) morning.

This diagram shows the moon’s travels through Earth’s shadow during tomorrow morning’s eclipse. The outer grey ring, called the penumbra, dims the moon’s light slightly. The real eclipse starts when the moon enters the dark inner core of the shadow (red) called the umbra. Times shown are Pacific Daylight. Credit: F. Espenak/GSFC

For Duluth and the Upper Midwest, the moon will set just as it enters the dark part of Earth’s shadow called the umbra. Ditto for locations further east. Die-hards will be able to see a slight shading before moonset when the moon is in the outer penumbral shadow, but the effect will be subtle. The further west you live, the higher the moon will be during eclipse. Those in the Pacific time zone will see it through maximum, when 54% of the moon will be covered, until it leaves the umbra at 6 a.m. PST. Since this eclipse occurs when the moon is low in the sky for most U.S. locations, it’s a great opportunity to get a cool picture with an interesting landmark or landscape in the foreground during twilight.

This map shows visibility zones for Saturday’s lunar eclipse. The "U1" curve shows where the moon sets just as the eclipse begins. Those living in the lower Midwest and Dakotas will see a little "bite" of shadow on the moon’s edge, while further west the entire event is visible. "U4", when the moon leaves the dark umbra, happens near moonset for West Coasters. Credit: F. Espenak/GSFC

Those of us who will miss this eclipse can take heart. Canada, the U.S. and South America will all get a wonderful total eclipse of the moon later this year on December 20 with the moon high up in a dark sky during the entire time. In the meantime, we welcome your eclipse reports and photos. 

Alpha Centauri is only visible from the latitude of southern Florida and points south. This view shows the star as seen from Honolulu. Alpha is just east of the famous Southern Cross; Proxima is about 2 degrees SW of Alpha. Created with Stellarium

After the sun, you’ll often hear that the nearest star is Alpha Centauri in the constellation of Centaurus the Centaur. Alpha is 4.4 light years (25.8 trillion miles) from Earth and the third brightest star in the sky, just a hair brighter than Arcturus. A small telescope will split Alpha into two stars — Alpha Centauri A and B — that revolve about their common center of gravity over a span of about 80 years.

Proxima is not nearly as distinguised as the mother star Alpha, but a small telescope will show it easily. Proxima’s orbit around the galaxy causes it to slowly move westward against the background stars as seen from Earth. Credit: ESO

Truth be told, the Alpha Centauri pair is not the closest star. That honor belongs Proxima Centauri, a diminuitive red dwarf companion of the A-B system. Alpha gets all the press because it’s bright and had its distance measured back in the 1830s. It stood as the closest star until Proxima was caught on a 1915 photographic survey seeking stars with unusually large motions across the sky. Closer stars appear to move faster than distant ones for the same reason a car zooming by in front of you appears to cover more ground than one at the same speed seen from a mile away. At 4.2 light years, Proxima is marginally closer to our solar system than Alpha. Marginal or not, that makes it no. 1.

The relative sizes of the sun and Alpha Centauri star system are shown in this diagram. A and B are solar-type stars while Proxima is a red dwarf. Credit: David Benbennick

Alpha Centauri A is slightly larger than the sun and one of the brightest stars, while Proxima is 11th magnitude and requires at least a 3-inch telescope to see. It’s almost certain that Proxima orbits the Alpha Centauri pair at a distance of 1.2 trillion miles or more than a thousand times Saturn’s distance from the sun. That’s so out there that Proxima’s located more than two degrees or four full moon diameters from the A-B pair and takes an estimated 500,000 years to complete an orbit around them.

Artist’s impression of a red dwarf star. Red dwarfs are reddish-orange in color and small but have plentiful starspots and flare activity. Credit: NASA

Why is the star so dim compared to its more famous sibling? It all comes down to size. Proxima’s a very tiny star, only 1.5 times the size of Jupiter, even though it weighs in with a mass 129 times larger. It belongs to the most populous group of stars in the galaxy called the red dwarfs. Red dwarfs burn their fuel in a miserly fashion compared to most other stars. That means they live long lives. Very long lives. When the sun runs out of nuclear fuel in four or five billion years and evolves into a blazing ember called a white dwarf, Proxima will still be humming along burning hydrogen and looking much the same as it does today for another few trillion years.

Given the stability and longevity of red dwarfs, you might think a planet in orbit around one would make great place for life to evolve. Maybe. Problem is that red dwarfs are known for their explosive flares, similar to the sun’s flares, but sometimes much more powerful. These could pose severe radiation problems for any planetary inhabitants. Dwarfs also vary in brightness because of both flares and starspots, which grow to enormous sizes and reduce light output up to 40%. Since we depend on the near constancy of the sun’s light, all this variability would impose great stress on most life forms.

The sun would be a bright first magnitude star below the W of Cassiopeia as seen from the Alpha Centauri system. Image source: Celestia

No star stands still. Proxima will remain the nearest star for another 32,000 years before our two stars drift apart. Its replacement will be Ross 248, another dim red dwarf, located 10 light years away in Andromeda and headed our way at this very moment.

Tomorrow we’ll talk about the upcoming lunar eclipse and International Space Station night-long marathons. Tonight you’ll see the station cross the sky twice beginning at 10:12 p.m. (across the south) and again at 11:47 (across the north).

The moon will be close to Antares tonight, the brightest star in Scorpius the Scorpion. Then early Saturday morning the full moon will undergo a partial eclipse for lucky viewers in the western half of the U.S. I’ll have details on Friday. Created with Stellarium

The Surveyor 6 landing location in Sinus Medii will be "in your face" this week as the moon waxes from gibbous to full phase. Photo: Bob King

As the moon waxes toward full phase this week, most of the sky’s fainter stars and galaxies will be snuffed out in its overwhelming light. This is the time many amateur astronomers discover they have nights free to do other things like spend a night on the town with their spouse or just get to bed early for a change. If you happen to step out in the moonlight tonight, fix your eye on the center of its glaring gibbous form. Although too small to see with the naked eye, there’s a small dark, lunar sea there called Sinus Medii (Central Bay). In November 1967 the Surveyor 6 probe soft-landed in the bay and studied the soil, took pictures and obtained other important data characterizing the lunar environment in advance of the manned Apollo missions.

The western horizon photographed by Surveyor 6 in November 1967 reveals the lingering glow of moon dust levitating about a yard above the surface. Credit: NASA

Among its data booty was a curious photograph of a glowing western horizon at sunset. On Earth the horizon glows after sunset because sunlight is still lighting up the atmosphere, but the moon has precious little of what you’d call air so this must have been something else. Further study revealed that the pictures captured the glow of electrostatically-levitating moon dust. The glow was seen by additional Surveyor landers.

The Clementine spacecraft took this photo of the sun’s corona rising over the moon’s edge just before sunrise in 1994. Venus is at top and the moon itself is lit by Earthshine or sunlight reflected off the Earth. Credit: NASA

As Apollo 17 astronauts orbited over the night side of the moon they planned to use the moon to block the brilliant sun so they could make observations of its faint outer atmosphere called the corona as well as a more extended glow of interplanetary dust particles illuminated by sunlight called the zodiacal light. Just before orbital sunrise, they saw what they expected — a hump of zodiacal light emerging from behind the moon’s edge — and something that surprised them, too. The entire curve of the lunar horizon glowed, and just before sunrise, the glow was shoot through with faint rays similar to the rays of light that beam through holes in the clouds in our earthly skies.

"Twilight" rays sketched by Apollo 17 astronauts just before sunrise
as they orbited the moon. Credit: NASA

Again, it was levitating dust at work, but this time, the dust was lofted to a height of 62 miles above the moon’s surface. Other Apollo crews saw similar phenomena while in lunar orbit. Scientists hypothesize that what the astronauts saw and Surveyor photographed was electrically-charged moon dust. Ultraviolet light and X-rays from the sun on the dayside of the moon are powerful enough to knock electrons, negatively charged particles, off lunar dust particles. This leaves the particles with a positive electric charge. Since like charges repel, the dust particles push away from one another and float in the direction of least resistance — up. The smallest particles reach the highest altitudes and then fall back to the surface, pulled down by the moon’s gravity. Others float up to replace them in a repeated cycle or rising and falling like the stream of water in a water fountain.

You can see and feel for yourself what’s happening on the moon if you take an inflated balloon and rub it on your hair (right). As you lift the balloon away from your head, your hair is drawn to the balloon. Rubbing removed electrons from your hair, giving the balloon an excess negative charge and your hair a positive charge. If you take the balloon away completely now, your hair will still stand up because each positively charged hair repels the other. A similar separation of electrical charges neatly explains repelling moon dust.

How about the lunar nightside? It appears that the dust there might be negatively charged because of electrons in the solar wind bombarding the soil. Astronomers speculate that nightside dust could float even higher than the dayside variety. Finally, there’s the interesting situation at the lunar terminator, the border between day and night. The terminator moves to the east as the moon’s phase waxes and to the west as it wanes. It’s a constantly shifting boundary. Timothy J. Stubbs of the Laboratory for Extraterrestrial Physics at NASA’s Goddard Space Flight Center, speculates there could be "significant horizontal electric fields forming between the day and night areas, so there might be horizontal dust transport. Dust would get sucked across the terminator sideways." Can you imagine standing astride the terminator as a lunar dust storm blew by — wow!

Fountains of lunar dust, strange glows. Just when we think the moon is dead, something new pops up like the recent discovery of lunar water, or in this case, levitating dust.

(Balloon photo credit: NASA)

A halo surrounds the sun on summer solstice morning in Duluth. Photo: Bob King

This is it. Welcome summer! This morning at 6:28 Central time the sun reached its highest point in the sky for the year in the constellation Taurus the Bull. Days are long, nights are short and the bugs have only begun their takeover. Since December, you and I and every other resident of the planet have journeyed over 292 million miles — half an orbit — to get here. Along the way we met Orion and Gemini, Canis Major and Cancer. They’ve fallen behind us now as we continue our carousel ride around the sun. Face the sky tonight and our neighbors are Scorpius, Sagittarius and the Summer Triangle.

As the Earth revolves around the sun, its axis maintains the same orientation but is tilted toward the sun in summer (for the northern hemisphere) and away from it in winter. Our tilted axis is responsible for the wonderful variety of seasonal changes on the planet. Credit: Tao’lunga

During summer the Earth’s northern hemisphere is tilted toward the sun like a listing fishing bobber. This tiny detail has profound consequences. If you’re tipped toward the sun, it appears higher in the sky than when you’re tipped away. Everything we know about summer follows from the sun’s altitude. The sun’s higher path means it’s up longer, increasing the length of day at the expense of night. A higher sun also means solar rays beam nearly straight down on us instead of from a low angle as in winter. Direct rays concentrate the sun’s energy, heat the air and ground more intensely and keep temperatures high. Put it all together and the plant and animal worlds have all the energy they need to party day and night.

We wake up to birds, hear bears in the woods, watch our grass grow and smile at the sight of fireflies at dusk. My neighbors are often up till 3 hollering and carrying on for totally non-astronomical reasons. Summer put them all up to it.

The difference in altitude between the summer sun and winter sun is 46 degrees or nearly five vertically-held fists at the end of your outstretched arm.

On any nice day, my old landlord Ed would always say to "better start countin’ ‘em", referring to the inevitability of the weather changing for the worse. Well, let’s bring Ed back for a moment to remind us that after today, the sun is headed back toward winter. Yes, we’re at the pinnacle, but only for a moment. Even as I write this, the sun has already begun its slide back down to where it came from; in six months days will again be short and sunlight diluted.

Not to be too concerned. We know that the sun’s slide is a s-l-o-w one, taking weeks before most of us notice that days are getting shorter again. That’s the meaning of the word solstice — "sun" and "standing still", referring to the considerable amount of time it takes for the sun to drop appreciably from its perch on high.

Just before sitting down to write, I heard one of my favorite pieces of summer music on the radio called Pastorale d’ete (Summer Pastorale) by Swiss composer Arthur Honegger. It has a lazy, dreamy quality that’s punctuated now and again by birdsong and beautifully evokes the season. Click on the video above to hear it. Do you have any favorite music that captures the essence of summer? Let us know by clicking on the comments link below.