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Northern Sky

East Bay Moon Crescent/Photo by Stephan Hoglund

Deane Morrison is a science writer at the University of Minnesota. She authors the Minnesota Starwatch column, and contributes to WTIP bi-weekly on the Monday North Shore Morning program through "Northern Sky," where she shares what's happening with stars, planets and more.

 


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Northern Sky: Oct 13 - 28, 2018

Northern Sky - by Deane Morrison
October 13 - 28, 2018

Deane Morrison is a science writer at the University of Minnesota.        
 
She authors the Minnesota Starwatch column, and in this feature, she shares what there is to see in the night sky in our region.

Deane Morrison’s column “Minnesota Starwatch” can be found on the University of Minnesota website at  astro.umn.edu. 

 

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Northern Sky: Sept 15 - 28

Norther Sky – by Deane Morrison  -  Sept. 15-28 2018

During the last two weeks of September, we have bright planets in the evening and a couple of regularly scheduled astronomical events.
 
If you face south 40 to 45 minutes after sunset, you’ll see Mars fairly low and still quite bright. Turning a bit westward, you’ll see the Teapot of Sagittarius, with Saturn above it. Next, even lower than Mars, there’s Antares, the red heart of Scorpius. Finally, low in the southwest, we have Jupiter. You probably won’t see Venus, though, especially later in the month, because it’s dropping into the sunset on its next trip between Earth and the sun. That trip also takes it, officially, from the evening to the morning sky.
 
As for stars, the Summer Triangle of bright stars is high in the south after nightfall. And in the west, the brilliant star Arcturus is still pulling its kite-shaped constellation, Bootes the herdsman, down toward the horizon. You might want to compare Arcturus with Vega, the brightest star in the Triangle and see if you can tell that Arcturus is ever so slightly brighter.
 
Now, about those scheduled events. First is the fall equinox. It arrives at 8:54 p.m. on Saturday the 22nd. At that point an observer from space would see the sun poised over the equator and Earth lighted from pole to pole. The equinox is also a crossover time of sorts. In spring and summer, the Northern Hemisphere tilts toward the sun, and the farther north you go, the longer the day length. But after the fall equinox, it tilts away from the sun and the days get shorter as you go north.
 
And, this is the time of year when the Northern Hemisphere is most rapidly shifting its tilt away from the sun. Which brings us to the second scheduled event: the harvest moon. Some say the harvest moon is the full moon closest to the fall equinox, others say it’s the first full moon after the equinox. This one qualifies on both counts. The full harvest moon, on Monday, September 24, rises over Grand Marais at 7:12 p.m., which is just two hours and 40 minutes before perfect fullness, so it’ll be nice and round.
 
But the harvest moon is more than just a name. Here’s how it goes. The full moon occupies a position on the other side of Earth from the sun—so it’s opposite the sun in the sky. Therefore, when we’re tilting most rapidly away from the sun, making it move south and rise later each day, we’re tilting most rapidly toward the full and nearly full moons and making them move north and rise relatively sooner each day.
 
Note that’s relatively sooner. The moon’s orbit makes it rise later from one day to the next; on average, around 50 minutes later. But around the time of the fall equinox, that interval gets slashed because of the moon’s rapid movement up through the northern sky. This year, for a few days centered on September 24, moonrise comes only 24 minutes later each night. That’s the harvest moon effect.
 
It’s fortunate for farmers, because it means that near full moon time, farmers harvesting crops don’t have to wait as long for a bright moon to come up and light their fields.
 
Finally, the rapid change in Earth’s tilt is sapping the day length faster than ever at this time of year, which I’m sure comes as no surprise. We’re losing around three minutes of daylight every day. But, I keep reminding myself, people in places like Alaska and Iceland have to put up with losses of six minutes a day.

 

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Northern Sky: Sept 1 - 14, 2018

Deane Morrison is a science writer at the University of Minnesota.
She authors the Minnesota Starwatch column which can be found on the University of Minnesota website at astro.umn.edu.

She tells us what to look for in the night sky in our region.

NORTHERN SKY – by Deane Morrison                      September 1-14 2018
 
Now that September’s here, the skies are getting seriously dark. Venus is still in the west, but it’s sinking fast. It’s also coming toward us, on the way to zipping between Earth and the sun. If you have a small telescope, you can watch it go through phases. Venus appears as a fat crescent now, but the crescent gets longer and thinner as September goes by. 
 
Somewhat high in the west, we have the brilliant star Arcturus. At this time of year, I like to watch Arcturus slowly fall through the sky from night to night. Arcturus is the brightest star in Bootes, the herdsman, a kite-shaped constellation, and it’s right where the tail of the kite would attach to the sail. So as Arcturus and Bootes drop down toward the horizon, it always seems as if this heavy star is dragging the kite down with it.
 
Actually, Arcturus is falling on a grander scale. It doesn’t orbit horizontally around in the disk of the Milky Way like the sun. Instead, its orbit slices right through the galactic disk. But Arcturus isn’t plunging through the disk by itself; it has more than four dozen stellar companions. Together the group is called the Arcturus stream. One caution: Don’t confuse Arcturus with Jupiter, which is bright but rather low in the southwest after nightfall.
 
Mars and Saturn come out low in the south. Mars is east of Saturn; it’s also brighter and, of course, redder than Saturn. Between the two planets is the Teapot of Sagittarius. Above all this, we have the large Summer Triangle of bright stars. The lowest is Altair, in Aquila, the eagle. It’s pretty much right above Mars. Looking up and a little west of Altair, you’ll see the brightest star in the Triangle. That’s Vega, in Lyra, the lyre of Orpheus. Note the parallelogram of stars below Vega; they outline the lyre and they make a really beautiful sight through binoculars. East of Vega is the third star, Deneb, in Cygnus the swan. Deneb also marks the head of the Northern Cross, a notable feature of Cygnus.
 
The Summer Triangle is a rich area of sky to explore, with both the naked eye and binoculars. And a star chart, if it’s your first time. Look above Altair—again, that’s the lowest star in the Triangle—and try to make out a short and skinny constellation called Sagitta, the arrow. Then try immediately northwest of Sagitta’s feathers and see if you can find the dim but astonishingly realistic Coathanger hanging upside-down. You’ll need those binoculars to make it out. Finally, look to the east-northeast of Altair for Delphinus, the dolphin, which seems to be happily leaping into a dark sea.
 
The moon is new on September 9.  For a couple days before then, there’s a thin old crescent moon in the east before dawn. On Saturday, the 8th, the moon rises close to Regulus, the brightest star in Leo. Then comes Mercury, and the sun right behind it. Look about 40 minutes before sunrise, and good luck seeing all three of the other objects when the sun is so close.
 
And, starting on the 8th, try looking for the elusive zodiacal light in the east, just before the sky starts to get light. The zodiacal light appears as a broad but faint glow along the sun’s path and it comes from sunlight reflecting off the dust that extends far out into space in the plane of the solar system. If you don’t find the zodiacal light on the 8th, the following two weeks will also be good times to look, and the moon won’t interfere with your view of the morning sky. 

 

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Northern Sky: August 18 - 31, 2018

NORTHERN SKY – Deane Morrison       Aug. 18-31 2018

At this time of year, the stars and planets have started coming out noticeably earlier. Venus is sinking, but still bright, in the west after sunset. The bright star Spica, in Virgo, is off to the left--our left--of Venus in midmonth. Spica is also dropping toward the western horizon, and it crosses paths with Venus on Friday the 31st. That evening, If you catch them when the sky's dark enough but they haven’t set yet, you’ll see Spica about two and a half moon widths above Venus.
 
Moving east, we have Jupiter, always bright. East of Jupiter and low in the sky is Scorpius, with Antares, the gigantic red star at the heart of the scorpion. Moving east again, we have the lovely Teapot of Sagittarius with Saturn shining above it, and finally Mars. Mars, Venus and Jupiter outshine all the stars, and Mars still outshines Jupiter. But Mars is fading as Earth leaves it behind in the orbital race, and soon Jupiter will reclaim its mantle as the brightest of the outer planets.
 
August's full moon arrives at 6:56 a.m. on Sunday, the 26th. However, the moon sets at 6:07 a.m. that day, so to see it you could go out around 5:30 a.m., or look for it the night before or the night after.
 
In astronomy news, you may have heard that on Sunday, August 12, NASA launched the Parker Solar Probe, an ambitious mission to the one star we can study up close. Parker will fly through the sun’s corona—its outer atmosphere—passing closer to the sun than any previous mission, and University of Minnesota space physicists play an essential role in it. Here’s the scoop.
 
It’s been known for decades that when subatomic particles escape from the sun’s surface their temperature is about 10,000 degrees Fahrenheit. But when they pass through the corona, they get heated to a few million degrees.
 
Scientists have debated how the corona heats these particles so intensely. And also, how the corona accelerates them and spews them out in a torrent of particles that barrels through space at up to a million miles per hour. This stream of particles bathes the solar system and is known as the solar wind.
 
Earth’s magnetic field intercepts the solar wind and shields us against it. When it collides with Earth’s magnetic bubble, it can lead to spectacular auroras. But when it’s fierce, the solar wind can knock out power grids, as it did in Quebec in 1989.
 
Whatever in the corona is heating and accelerating these particles has to be electric and magnetic fields, because that’s all there is. The debate is about the details. The Parker spacecraft carries an instrument, designed by U of M researchers, to study the corona’s electric and magnetic fields and particles. This data will help settle the debate and make it easier to predict the heaviest gusts of the solar wind and take precautions to protect power grids.
 
How close will Parker get to the sun? If Earth and the sun were at opposite goal lines on a football field, the closest any spacecraft has come is the sun’s 29-yard line. But Parker will zip inside the 4-yard line, less than four million miles from the sun. NASA has dreamed of such a mission for 50 years, but the technology took time to develop. For example, engineers had to design a heat shield that’s capable of deflecting temperatures high enough to melt steel. Also, the Parker Solar Probe must, by itself, adjust its orientation to keep its heat shield between the spacecraft and the sun as it hurtles through its tightest loop around the sun at more than 400,000 miles per hour.
 
 
 

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Northern Sky: July 21 - Aug 3, 2018

Deane Morrison is a science writer at the University of Minnesota.

She authors the Minnesota Starwatch column, and in this feature she shares what there is to see in the night sky in our region.
Deane's column can be found on the University of Minnesota website at astro.umn.edu.

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Star Watch - Late July

Northern Sky: July 7 - 20, 2018

Deane Morrison is a science writer at the University of Minnesota.

She authors the Minnesota Starwatch column, and in this feature she shares what there is to see in the night sky in our region.
Deane's column can be found on the University of Minnesota website at astro.umn.edu.

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June 2018

Northern Sky - June 9-22

Northern Sky  -  by Deane Morrison  June 9-22 2018

During the two weeks between June 9 and 22 the moon switches from the morning to the evening sky. It starts out as a waning crescent that drops diagonally toward the sun from morning to morning. On the 13th we get a new moon, at which point the moon crosses to the evening sky and begins waxing.
 
In the western evening sky, Venus continues to outshine everything else. Starting on the 9th, the Gemini twins, which have been dropping toward Venus, start to pass the planet on the right, or, its northern side. The Gemini twin stars are Castor and Pollux, Pollux being the one closer to Venus. On their way toward the horizon, the twins pass the young moon on its way up.  
 
We can see this after nightfall on Friday, the 15th. We’ll have a young crescent moon below Venus and the Gemini twins off to the side. When the sky has darkened on the 16th, grab your binoculars and look for the lovely but subtle Beehive star cluster midway between Venus and the moon. You’ll see two stars bracketing the Beehive to the upper left; these are the Aselli, or asses. In Latin the Beehive is called Praesepe, the manger, and the Aselli are two donkeys feeding at it. On the 19th, the Beehive will appear immediately southeast of Venus, that is, just to its lower left, but by then we’ll have a nearly first-quarter moon that might wash out the stars a bit.
 
Jupiter is up in the south after nightfall. To the west of Jupiter is the bright star Spica, in Virgo. Actually, it’s the only bright star in Virgo. Above these two objects is Arcturus, in Bootes, the herdsman, a kite-shaped constellation. Just east of the kite is Corona Borealis, the northern crown, which looks like a tiara hanging in the sky. Its brightest star is Alphecca, or Gemma, the jewel in the crown. Alphecca is a double star, a pair of stars, one significantly fainter than the other. It’s an example of what’s known as an eclipsing binary. Every 17.4 days, the fainter star passes in front of the brighter star as seen from Earth and causes a slight dip in Alphecca’s brightness. The most famous eclipsing binary is Algol, in the winter constellation Perseus. The variations in its brightness are easily seen. To the ancients it looked like a winking eye in the sky.
 
If you’re up late, camping or just outside with a southern exposure, you can watch the summer stars follow Jupiter into the sky from the southeast. First Scorpius and its gigantic red heart, Antares. Then the Teapot of Sagittarius, with Saturn shining above the lid of the Teapot, and finally Mars, which is brightening by the day. Everything rises earlier every night, but practically speaking, you won’t see Mars till after midnight.
 
The summer solstice happens at 5:07 a.m.—almost exactly sunrise in Grand Marais—on Thursday, the 21st. At that moment the sun reaches a point over the Tropic of Cancer and Earth will be lighted from the Antarctic Circle up to the North Pole and over to the Arctic Circle on the night side of the planet. You may have noticed that the sun is about as high as it gets for about a month before and after the summer solstice. And about as low as it gets for two months centered on the winter solstice. That’s because, of course, the sun moves northward and southward most slowly around the solstices, when it changes direction and appears to stop for a while. In fact, the word solstice is derived from the Latin for “sun standing still.”

Deane Morrison is a science writer at the University of Minnesota.
She authors the Minnesota Starwatch column, and in this feature, she shares what there is to see in the night sky in our region.

"Minnesota Starwatch" can be found on the University of Minnesota website at 
astro.umn.edu.
 

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June Sky

Northern Sky: May 26 - June 8

Northern Sky  –  May 26 – June 8, 2018
 
May closes out--almost--with another full moon, the full flower moon. The moment of fullness arrives at 9:19 a.m. on Tuesday, the 29th. But by then the moon will already have set, so if you want to see it, go outside at sunrise. It'll be over in the west, looking pretty against a pale sky.
 
If you're up even earlier that day, say, 90 minutes before sunrise, you'll have a great view of stars and planets. Like Jupiter getting ready to set in the west. Or the moon right above the crown of Scorpius, a more or less vertical curved line of three stars very low in the southwest. Just southeast of the moon you'll see the scorpion’s red heart, Antares, the rival of Mars. East of the moon are two bright objects. One is Saturn. It's just above the Teapot of Sagittarius, a lovely star pattern that actually looks like a teapot. These mornings it tips its spout as if to pour tea on the stinger of the scorpion. Earth is catching up to Saturn in the orbital race, and on June 27, we lap the ringed planet, and it'll be at its brightest.
 
The other bright object is farther east, and that's Mars. Mars is already starting to dazzle us with its growing brilliance. That's because, as I've been saying, it, too, is going to get lapped by Earth soon. At the end of July, in fact--just a month after Saturn. Above Mars, the Summer Triangle of bright stars twinkles away. And, wouldn't you know it, gaining altitude in the east is the Great Square of Pegasus, an autumn constellation.
 
After full moon, the moon continues its way eastward. On June 1, it'll be between Saturn and the Teaspoon, a curved line of stars hanging down over the handle of the Teapot. On the 2nd it'll be between Saturn and Mars, and on the morning of the 3rd it hovers over Mars; these two objects will look like a big pearl above a small ruby. After passing Mars, the moon glides through a relatively dim starfield on its way to becoming new.
 
In the evening sky, we have Jupiter again. It's up in the southeast by nightfall, very bright but no match for Venus. The planets I mentioned earlier follow Jupiter into the sky, but not all of them make it during the evening—that is, pre-midnight—hours. As for Venus, it continues to blaze away in the west. During the first week of June the Gemini twins Pollux and Castor drop toward the planet. The brighter twin, Pollux, is the one closer to Venus. During the last several days of May and into June, the twins and Venus form a triangle that starts out long and thin but then shortens and flattens as these three objects shift positions. By Friday, June 8, they'll have formed one of the flattest triangles in history. The twins are among the last of the winter stars to head into the sunset, but they'll all reappear in the morning sky by late summer.
 
Turning a little to the north from Venus, you may see Capella, a gorgeous multicolored winter star. It's the brightest in Auriga, the charioteer, but with so many bright stars up in the winter, it may get kind of lost in the shuffle.
 
Also after nightfall, we have Spica, in Virgo, the next bright object west of Jupiter. If skies are dark, you might want to grab a star chart and try to trace the form of Virgo. Spica is the constellation's only bright star, so it can be a challenge to find Virgo the first time.
 

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Northern Sky: May 12 - 25

Northern Sky -  by Deane Morrison - May 12-25 2018
 
 
For a week starting Saturday, May 12, we have morning and evening skies that are free or nearly free of moonlight, and that makes for good starwatching. The moon becomes new in the early morning of the 15th, then starts its next march eastward across the evening sky. As it goes, it gets bigger and brighter and sets later, so we have less and less time to see celestial objects without the moon washing everything out.
 
On evenings around new moon, look for Leo, the lion, high in the southwest. Its most prominent feature is a backward question mark of stars, known as the Sickle. The dot of the question mark is Regulus, the brightest star in Leo. Regulus is also the sharp point of a stellar triangle; the other two stars are brilliant Arcturus, which is high in the south at nightfall, and Spica, which is below Arcturus. Arcturus is the anchor for the kite-shaped constellation Bootes, the herdsman, and Spica is the only bright star in Virgo. These days Spica and Arcturus are also part of another triangle, with Jupiter. Jupiter is a beacon in the east, near the peak of its brightness. Also, just to the southwest of Spica you’ll find a four-sided figure. This is Corvus, the crow—another of those constellations that aren’t very prominent but can be fun to find.
 
On Wednesday, the 16th, look for a very young crescent moon down by the horizon below Venus—that brilliant light in the west. The next night, the 17th, the waxing moon will have moved to about the same level as Venus. On the 18th, a fatter crescent appears below Pollux, the brighter of the Gemini twins. The other twin, Castor, is to the right of Pollux. On Monday the 21st, a first-quarter moon will be practically sitting on top of Regulus. And the evening of the 25th, a bigger, brighter moon appears above Spica.
 
If you have a lawn chair, you may want to grab it and look for Ursa Major, the great bear. It’s really high after nightfall these days, close to the overhead position, hence the advisability of observing from a reclining position. You may also need a star chart to make out the whole constellation. The Big Dipper is the bear’s hindquarters and tail, and the arc of the tail—which is also the handle of the dipper—leads you to Arcturus. Just remember “arc to Arcturus.” At the bend of the handle is a famous double star. Binoculars will bring them out nicely. The stars are Mizar, the brighter one, and Alcor, its fainter companion. These two have also been dubbed the horse and rider.
 
Also, I enjoy looking for three tight pairs of stars that represent the paws and one hind foot of the great bear—although not all star maps indicate that. The three pairs of stars form a diagonal line below the bowl of the Big Dipper and they have been named the Three Leaps of the Gazelle. They’re also not prominent, but they’re one—or three—more things that can be fun to find.
 
In astronomy news, NASA just launched its InSight mission to Mars. InSight is designed to find out, as NASA puts it, “what makes Mars tick.” The lander will plant a seismometer on Mars. It’ll study Mars quakes, and the mission will also track how heat in the interior of the planet gets dispersed, and how Mars wobbles. It may even be able to detect liquid water or plumes of active volcanoes below the Martian surface. All this data will shed light on the formation of other rocky planets, including Earth and the moon. Landing is scheduled for November 26th.

 

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May Night Sky

Northern Sky: April 28 - May 11, 2018

Northern Sky by Deane Morrison for April 28 - May 10 2018

April's weather has been forgettable, but on the evening of the 29th it gives us a gorgeous full moon. Perfect fullness happens at 7:58. That's just minutes after moonrise in Grand Marais, so when it first clears the eastern horizon it'll be one of the roundest moons ever. April's full moon is called the full pink moon, after wild ground phlox, also known as grass pink, a small pink flower that carpets the land this time of year. This full moon won't be especially large or small, but if you can get outside just before eight o'clock on Sunday, the 29th, it will be worth it.
 
The next night is a treat for anybody who follows the Celtic holidays. It's April 30, the eve of May Day. According to old Celtic tradition, sundown on April 30 was the beginning of the holiday known as Beltane. It signified the end of the dark half of the year, which began at sundown on Halloween. The critical events that defined the dark and light halves of the old Celtic year had to do with evil spirits. At sundown on Halloween, they came rushing out of exile and started causing illness and otherwise making trouble, but at sunrise on May 1 they disappeared into exile again, and the light half of the year began. Beltane, or May Day, and Halloween are astronomically based holidays. They're what's known as cross-quarter days and they fall more or less halfway between an equinox and a solstice. Groundhog Day is another one, but the fourth cross-quarter day doesn’t get much press. That’s Lughnasa, a harvest holiday at the beginning of August.
 
As we get into May, the moon will be waning and spending less time in the evening sky. Be sure to have a look at Venus; it's the bright object that comes out in the afterglow of the setting sun. In the east, Jupiter is a rival beacon. These are the two brightest planets, and when darkness falls you can compare them not just in brightness but in color. On the night of the full moon, Jupiter rises below the moon and follows it across the sky.
 
Jupiter is about as bright as it gets now because Earth laps it in the orbital race early on the night of May 8th. That event is called opposition because it puts Jupiter opposite the sun in the sky. At opposition an outer planet rises around sunset and sets around sunrise. On the 10th, Jupiter and Earth come within about 409 million miles. That's their closest approach, and it comes after opposition because Earth is moving farther from the sun while Jupiter is moving in, and that brings them closer before speedier Earth pulls away.
 
For early risers, we still have, in this order, Mars, Saturn and Jupiter strung from left to right across the predawn sky in the south. This string of planets is lengthening as Mars moves eastward against the background of stars while Saturn and Jupiter move westward. Saturn and Jupiter appear to move westward against the stars, in what's called retrograde motion, now because they’re at or nearing opposition. When Earth is lapping one of the outer planets, the act of passing it by makes it appear to move backwards, or westward, even though the planet’s own motion carries it eastward. It's the same when a runner in an inside lane laps a runner in an outer lane. The outer runner will seem to move in the opposite direction from how he or she is actually moving. Saturn reaches opposition in late June, Mars not till late July.
 

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