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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 Map.  Courtesy Deane Morrison.

Northern Sky: August 31 - September 13

NORTHERN SKY
by  Deane Morrison
August 31 - September 13, 2019

Over Labor Day weekend, the moon is a young sliver that sets before or shortly after nightfall. Each night it moves farther eastward, on its monthly tour of the sky. It’s waxing brighter now, and won’t begin withdrawing from the evening sky until after the full phase in mid-September. So if you’re an evening star watcher and you go out during the two weeks after Labor Day, you’ll probably be seeing a lot of the moon.  

As for the stars, this month the Summer Triangle is high in the south, in prime position for evening viewing. The brightest of the three stars, Vega, in the constellation Lyra, the lyre, is just a hair less bright than the star you may have noticed slowly sinking in the west. That’s Arcturus, the anchor of Bootes, the herdsman, and the brightest star in the northern hemisphere of the sky. In the east, the Great Square of Pegasus, a fall constellation, is climbing into prominence.

Every year the stars and constellations are the same, but the planets move around. This summer, we’ve been treated to the sight of Jupiter and Saturn in the south after nightfall—and Jupiter is so bright, it comes out in the twilight, well before Saturn. On the 5th, the waxing moon hovers near Jupiter and almost directly above Antares, the brightest star in Scorpius. At 10:10 that night, Thursday, the 5th, the moon reaches first quarter phase. When the moon is at a quarter phase, the features of the lunar surface cast the deepest shadows, and this makes them stand out in sharpest relief. So this is a good night to explore the lighted part of the moon with binoculars. You don’t have to wait till after ten o’clock, of course; the moon is essentially at the first quarter phase all evening.

On the 7th, the moon will be bigger and brighter, this time closing in on Saturn. You may need binoculars to see it, but the star a few degrees below and right of the moon is the lid of the Teapot of Sagittarius. The Teapot will be somewhat washed out by moonlight, but if you haven’t seen it yet and would like to, that’s where to look for the lid, at least. On the 8th, the moon will be east of Saturn. On the 10th, the moon will be in the middle of the constellation Capricornus, the sea goat. Capricornus is chevron-shaped, and it’s one of the autumn water constellations. It has no bright stars, so it’s hard to find. But if you note where the moon is on the 10th and then find a star chart, that’ll vastly improve your chances of finding this dim constellation of the zodiac.

Three days later, on the 13th, we get a full moonrise. In Grand Marais, the moon rises at 7:36 p.m., four hours before it becomes perfectly full. Because it’s the closest full moon to the equinox, it qualifies as the harvest moon. The harvest moon got its name because near the time of the fall equinox, the moon can rise less than 30 minutes later from night to night as it goes from almost full to full to a couple of days past full, as opposed to forty or fifty minutes later from night to night near the solstices and more than an hour later from night to night near the spring equinox. The harvest moon gave extra moonlight to farmers working late to harvest their crops before they either froze or spoiled in the field. The harvest moon effect isn’t always as strong as the numbers I just gave would imply, but even so, this nickname for a full moon has a pretty solid basis. 
 

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Star Map July 2019 by Deane Morrison

Northern Sky: July 20 - Aug 2

NORTHERN SKY - Deane Morrison
July 20 - August 2, 2019

Today, in honor of the 50th anniversary of the moon landing on July 20, I’d like to talk about how it happened and why it was scientifically important.
 
On July 20, 1969 the moon was a waxing crescent in the evening sky. The Apollo 11 astronauts had a landing site all picked out near the border with Earth’s shadow, where it was just past sunrise. As the computer aboard the lunar module, the Eagle, guided them down, Neil Armstrong and Buzz Aldrin watched the moonscape go by below them. At about 33,000 feet, an alarm suddenly went off. Nothing in their training had prepared them to figure out what it was. They spent several minutes trying to identify it before Mission Control finally told them not to worry; it was just the Eagle’s computer reacting to being overloaded.
 
While the astronauts were chasing this wild goose, the lunar module used a lot of propellant fuel, and when the fuel tank dipped to half full, the propellant started sloshing around and knocking the module every which way. The sloshing also set off a “low fuel” alarm prematurely, and so the crew thought they had less time to land than they actually did.
 
These issues also kept Armstrong from checking out the landing site visually. At about 2,000 feet, he finally did, and he saw that the site was a boulder field—not smooth ground at all. At about 540 feet, Armstrong took manual control of the spacecraft. Despite the disruptions, he was able to guide the lunar module past the boulder field and set it down with just 20 seconds left before they would have been forced to land wherever they were or abort the landing.
 
Apollo 11 brought back 46 pounds of moon rocks. In all, 842 pounds of moon rocks came back on Apollo spacecraft. The oldest are 4.5 billion years old, same age as Earth. They indicated that the moon, like Earth, was also once covered by an ocean of magma. But unlike Earth, which has an iron core, the moon has very little iron and came from the same stuff as Earth’s mantle. These findings support what was once a radical idea: that the moon didn’t condense out of the same cloud of solar system material as Earth, nor was it captured later by Earth, but it formed when another planetary body collided with an infant Earth that was still molten. The collision knocked out material from Earth’s mantle, and perhaps from the other body, and this material coalesced to become the moon.
 
Also, moon rocks record impacts from collisions, and the number of impacts apparently spiked around 700 million years after Earth and the moon formed. An explanation for why so many more objects should have been flying around the solar system and hitting the moon—and Earth, of course—at that time is part of a leading theory of how the solar system formed. Simply put, it says that early on, gravitational interactions between Jupiter and Saturn destabilized the entire solar system and pushed the orbits of Saturn, Uranus and Neptune farther out. This changing gravitational landscape disrupted the orbits of numerous small bodies far from the sun, collectively called protoplanetary debris, and scattered them throughout the solar system. The result was an outbreak of collisions that lasted until most of the debris was cleared. And this outbreak, called the late heavy bombardment, left its signature in the spike of impacts imprinted in the moon rocks.

Scientists are still debating exactly how the moon formed and what the moon rocks tell us. But by any measure, these rocks are among the most valuable items of all time.
 
Deane Morrison writes the Minnesota Starwatch column for the University of Minnesota’s Minnesota Institute for Astrophysics.
 


 
Star Map June by Deane Morrison

Northern Sky - Deane Morrison June 8 - 21

NORTHERN SKY
by  Deane Morrison
June 8-21 2019
 
In the second two weeks of June, planets and stars are on the move. But the sun seems to be standing still, as it always does for about two months around each solstice, a word that literally means “sun standing still.” The summer solstice arrives at 10:54 a.m. on Friday, the 21st. At that moment, the sun will be over the Tropic of Cancer, and an observer in space would see the Earth lighted from the Antarctic Circle up to the North Pole, then beyond to the Arctic Circle on the dark side of our planet.
 
In the west, Mercury has popped into the evening sky. Mercury never gets very high, but if you look at nightfall from night to night, with binoculars if necessary, you may be able to see it climb away from the west-northwestern horizon. It heads straight for Mars, which is extremely dim, and on the 18th it passes only about half a moon width above the red planet. Above and to the right of the planets are the Gemini twins Pollux, the brighter one, and Castor. After their close encounter, Mars and Mercury go their separate ways. And all these objects get lost in the sunset by the end of June.
 
On the 10th, we lap Jupiter in the orbital race. At this moment Jupiter is said to be at opposition, because it’s on the opposite side of Earth from the sun and thus opposite the sun in the sky. At opposition, an outer planet rises around sunset and stays up all night. Jupiter is a brilliant beacon, and it rises in the southeast right behind the constellation Scorpius. The scorpion’s heart is Antares, a gigantic red star a little below and west of Jupiter. Saturn follows Jupiter into the sky by about two hours.
 
The evening of the 15th, a bright waxing moon appears between and above Jupiter and Antares. The evening of the 18th, a bright waning moon rises right below Saturn. For the next several days, Jupiter and Saturn get to shine against a darker sky at nightfall because the moon rises later each night while they rise earlier.
 
In the east, look for the Summer Triangle of bright stars. The brightest is Vega, in the constellation Lyra, the lyre of the mythical Greek musician Orpheus. With binoculars you can easily see the parallelogram of stars that outline the body of the lyre. Vega is only about 25 light-years away, and it has a great claim to fame, thanks to Earth’s habit of wobbling on its axis like a top. This wobbling makes the North Pole point to different stars in sequence as it traces out a circle every 26,000 years. The North Pole now points toward Polaris, but once it pointed toward Vega, and in about 12,000 more years, Vega will again be the north star.
 
When the sky gets dark, Vega and Jupiter form a big, bright triangle with the brilliant star Arcturus, in Bootes, the herdsman. Arcturus is west of Vega and marginally brighter. Grab a star map and look between Vega and Arcturus. Next to Vega is the upside-down form of Hercules, and next to Hercules is a semicircle of stars called Corona Borealis, the northern crown.
 
The night of the 16th to 17th, the moon takes a low trajectory across the night sky and reaches fullness at 3:31 a.m. The low trajectory happens because a full moon is always opposite the sun in the sky. Therefore, when we’re this close to the summer solstice and our hemisphere is tilting strongly toward the sun, it must also tilt away from a full moon, leaving it low in the sky. 
 
 
Deane Morrison writes the Minnesota Starwatch column for the University of Minnesota’s Minnesota Institute for Astrophysics.
 

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Sky Map_June 2019 by Deane Morrison

Northern Sky: May 25 - June 7, 2019

NORTHERN SKY  by Deane Morrison
 
During the last week of May, the moon wanes away in the morning sky, starting with the last quarter phase on Sunday, the 26th. Last time, I mentioned that the quarter phases are good for moon watching because that’s when lunar features like craters stand out in sharpest relief. So on the 26th, you may want to grab your binoculars again. One small caveat: In Grand Marais, the moon doesn’t rise that day until 2:09 a.m., which may be somewhat inconvenient. On the other hand, if you’re a night owl, the last quarter phase gives you the best chance to explore the part of the moon that isn’t visible at first quarter phase.
 
If you are up at that hour, you’ll see the Summer Triangle of bright stars above the moon as it rises in the east-southeast, plus Jupiter—the brightest dot—in the south and Saturn to the lower left of Jupiter. But you don’t have to wait till the middle of the night to see those planets. Earth is about to lap them in the race around the sun, and they’re rising earlier every night. We lap Jupiter on June 10, and by the end of the first week in June, Jupiter will up in the southeast by 10 p.m. Saturn follows Jupiter by about two hours. Just west of Jupiter is the red star Antares, the heart of Scorpius.
 
You might want to try watching Jupiter from night to night. Earth is already starting to lap it, and this makes it moves westward against the backdrop of stars. If you grab those binoculars again, you may detect Jupiter inching westward with respect to several rather dim stars that are near the planet.  
 
And back to the moon for a second. As it wanes, it rises later every morning. If you’re up around 4:30 on June 1 and you have a clear view of the eastern horizon, you may see a very old and thin crescent rising to the lower right of Venus. Moonrise on June 1 is at 4:27 a.m., which is scarcely half an hour before sunrise, so both the moon and Venus will be awash in the sun’s foreglow. 
 
In the evening sky, Spica, the brightest star in Virgo, the maiden, is in the south at nightfall, well below the brilliant star Arcturus. Spica’s not all that bright, but then it’s about 260 light-years away. It’s not a single star, but at least two big ones that orbit each other very closely. Only 11 million miles apart, which is about one-fourth the distance of Mercury from the sun. The strong gravity between these two stars has pulled each of them out into an egg shape, and it’s thought that they spin around like two gigantic eggs with their narrow ends pointed at each other. And they spin really fast: It takes them only four days. This would be incredible to watch if we could get close and look down on these stars.
 
In the west, Mars is resisting being swallowed by the sun as Earth leaves it behind. Mars is as dim as it gets, but have a look around 40 minutes after sunset on June 4. Mercury will be very low in the west-northwest, a young crescent moon will be just to the left of it, and Mars will be almost directly above the moon. Above Mars, the Gemini twins Pollux, the brighter, and Castor are dropping as they make their seasonal exit from the evening sky. This year they’ll leave in the company of Mars and Mercury.
 
Deane Morrison writes the Minnesota Starwatch column for the University of Minnesota’s Minnesota Institute for Astrophysics.
 

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May 2019 Star Map.jpg

Northern Sky: May 11 - 24, 2019

NORTHERN SKY  by  Deane Morrison                May11-24, 2019

 
Here in mid-May, we have two planets that are fairly bright and busy moving into prime viewing position. Those planets are Jupiter and Saturn, and they’re rising in the southeast earlier every day, but still pretty late. Jupiter makes it up before midnight, but Saturn doesn’t; it follows Jupiter around two hours later. You can also see them in the predawn sky, say 4 to 4:30 a.m. Jupiter is the brightest thing after the moon, and Saturn the next brightest thing to the east of Jupiter.
 
The planets are about 27 degrees apart, which isn’t very far. Not coincidentally, Earth is getting ready to lap both of them in the race around the sun. Jupiter on June 10, Saturn on July 9. When we lap an outer planet, it’s up all night, which is ideal for viewing. However, summer’s coming, our hemisphere is tilting away from the night sky, and the sun has stolen a big chunk of it. Right now, we can only see Jupiter and/or Saturn very late in the evening or ridiculously early in the morning.
 
On top of that, between May 11 and 24, the period this broadcast covers, the moon will be big and bright enough to wash out a lot of the stars that form a backdrop for the planets.
 
Well, if you can’t beat ‘em, join ‘em. Let’s look at what the moon can do for us. The evening of the 11th, it’ll be at first quarter phase. This is a good time to pull out your binoculars or small telescope and have a look at the moon. During quarter phases, the moon is 90 degrees from the sun, and lunar features, like craters, appear in sharp relief. Just east of the moon, you’ll see Regulus, the brightest star in Leo, the lion. Regulus is the dot in a backward question mark of stars called the Sickle, which outlines the lion’s head.
 
A night or two later, on the 12th or 13th, the moon will have moved farther east in Leo. The lunar features will still stand out, and a famous one will now be lighted. That’s the Tycho crater, which was named after the great Danish astronomer Tycho Brahe, who died in 1601 at age 54. The crater is near the south pole of the moon and is about 53 miles across. It’s remarkable for the long bright lines radiating from it; these are where material was thrown during the collision with whatever space rock came along and gouged out the crater. The crater has been estimated to be about 100 million years old, which is young for a lunar feature.
 
Between the 15th and 16th of May, the moon passes between Spica, the only reasonably bright star in Virgo, and brilliant Arcturus, in Bootes, the herdsman. Spica will be below the moon, and much closer to it than Arcturus.
 
May’s full moon rises over Grand Marais at 8:27 on the evening of the 18th. It crosses the night sky above Antares, the red heart of Scorpius. Over the next several days, the waning moon sweeps past Antares, then Jupiter and Saturn.
 
In the north, the Big Dipper hangs more or less upside down at nightfall. The two stars at the far end of its bowl—that is, farthest from the handle—point down to Polaris, the North Star. Flanking Polaris, but closer to the horizon, are two bright stars. On the left is Capella, in Auriga, the charioteer, and to the right is Vega, the brightest of the Summer Triangle of bright stars. And if you follow the curve of the Big Dipper’s handle, it’ll take you to Arcturus again.
 
Deane Morrison writes the Minnesota Starwatch column for the U of M’s Minnesota Institute for Astrophysics.
 

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May 7 Skymap.jpg

Northern Sky: April 27 - May 10, 2019

NORTHERN SKY  by Deane Morrison
April 27-May 10 2019

Here we are again, moving from April into May, and the winter stars are disappearing in the west. But they’re not all gone yet. Case in point, a little while ago, a friend asked me about a couple of bright stars he had seen in the west around nine thirty the night before. Both were about the same distance above the horizon. So I took a good guess, and went out that night, and sure enough, what had caught his eye was the winter stars Procyon, in Canis Minor, the little dog, and Capella, in Auriga, the charioteer. Right now these two stars are getting ready to set for the season. If you haven’t seen them but you’d like to, go outside as soon as the sky gets dark, and you should see two bright stars not far above the western horizon. Procyon is on the left, Capella on the right. Above and between them are the Gemini twins, Pollux, that’s the brighter twin, and Castor.

This winter I’ve talked about all these stars except Capella. It’s a beautiful star, and when it’s low in the sky, Earth’s atmosphere often acts like a prism and makes it twinkle red and green. From the latitude of Grand Marais, it’s a circumpolar star. That is, it travels in a circle around the Pole Star, Polaris, and never sets, although in summer it gets a little too low to see very well. The stars of the Big and Little Dippers are also circumpolar. If you could follow a circumpolar star all day long, you’d see it complete one circle around Polaris every day. And if you noted its position at the same time every night for a year, you’d see it circle Polaris then, too.

Capella is also a multistar system. It has a close pair of big yellow stars, both a lot brighter than the sun and with about 2.5 times its mass. It also has a pair of little red dwarf stars orbiting the big yellow stars at a distance of about 10,000 times the distance of Earth to the sun.
The name Capella refers to the “little female goat” that the charioteer is carrying. Below Capella you may be able to make out three fainter stars that form a narrow triangle. These are called the Kids.

On May 7, Capella will be part of a string of objects lined up diagonally from lower left to upper right at nightfall, but not much longer afterward. Starting at the lower left end, we have Betelgeuse, in Orion; then a young crescent moon; then Mars, and finally Capella. On the evening of May 9, a heftier crescent moon will be between Procyon and Pollux.

And speaking of evenings, sundown on April 30 marks the beginning of the astronomically based Celtic holiday called Beltane. It was one of four cross-quarter days falling midway between an equinox and a solstice. Beltane marked the end of the dark half of the old Celtic year. The dark half began at Halloween, when all the evil spirits were set loose upon the world to vex humankind for the next six months. And that made sense; winter is the time when hunger, cold and diseases like flu run rampant. But when the end of April rolled around, things changed. At sundown on April 30, the nasty spirits came out for a last fling. Then, at sunrise on May 1, the party was over, and the spirits were again banished until sundown on October 31. The night of April 30 is also called Walpurgis night, but only because May 1 is associated with St. Walpurga, who had nothing whatsoever to do with any of this.
 

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April Star Map - MN Starwatch

Northern Sky: April 13 - 26, 2019

NORTHERN SKY – by DEANE MORRISON    
April 13-26 2019
 
Well, what a difference a day makes. On Wednesday, April 10, a colossal astronomy story broke. Scientists working from radio telescopes all over the world released the first direct image of a black hole. Apologies if you’ve already heard all about this, but here goes.
    
Black holes are typically found at the centers of galaxies. They concentrate matter so densely, and generate such strong gravity, that nothing that gets too close can escape, including light. The boundary beyond which escape is impossible is called the Event Horizon, and that’s the name of the team that produced the image.
    
This black hole shows up as a dark round area inside a fuzzy, lopsided doughnut of light. It lies at the heart of a monster galaxy called Messier 87, which is one of the most massive galaxies in a cluster of galaxies in the constellation Virgo. The Virgo Cluster is in the general neighborhood of our Milky Way galaxy, and both the Milky Way and Messier 87 are powered by supermassive black holes.
    
But there’s no comparison. The mass of the Milky Way’s black hole is equal to 4 million suns, while Messier 87’s black hole has the mass of 6.5 billion suns; that’s 1,600 times more. The researchers calculated the diameter of the black hole to be 40 billion kilometers, or 25 billion miles. That makes it more than four times the diameter of Neptune’s orbit and nearly the size of our entire solar system. The Messier 87 galaxy is about 55 million light-years away. It’s visible through a small telescope, and May is a good month to observe it.
    
If you want to see where in the sky this galaxy is, and maybe point out its location to children or friends, you can use stars to navigate. Start by facing south after nightfall, at 9:30 or so. You’ll see the constellation Leo, the lion, fairly high in the south. Its brightest star,  Regulus, is the point in a backward question mark of stars that outline the lion’s head. Just east of the lion’s head is a triangle of stars marking the tail and hindquarters. The brightest and most eastern of these stars is Denebola. Okay, remember Denebola. Moving eastward again, you’ll see brilliant Arcturus, not quite as high as Denebola. Much lower, between Denebola and Arcturus, is Spica, the brightest star in Virgo.
    
Put another way, we have brilliant Arcturus well up in the east, Spica far to the lower right of Arcturus, and relatively dim Denebola to the upper right of both. These three stars form a nearly equilateral triangle. In fact, they are often called the Spring Triangle.
    
If you look from Arcturus about three quarters of the way to Denebola, and then down a little, that’s where M87 and its black hole, its heart of darkness, are. On April 17 the moon visits; if you point to a spot directly west of Arcturus and above the moon, you won’t be far off.
       
In the morning sky, Jupiter and Saturn, along with the star group known as the Teapot of Sagittarius, are slowly making their way westward, like a convoy. Jupiter is kind of low but brilliant, Saturn is the next bright object to the east, and the Teapot is between them. The moon visits Jupiter on the 23rd; on the 24th it sits right above the lid of the Teapot, and on the 25th it visits Saturn.
     
April’s full moon arrives on Friday, the 19th at 6:12 a.m. That’s shortly after sunrise and before moonset in Grand Marais. With clear views to east and west, you’ll see a rising sun and a very round, setting moon facing each other from opposite horizons.
 

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Deane Morrison - photo via LinkedIn

Northern Sky: March 30 - April 12, 2019

Northern Sky by Deane Morrison
March 30 - April 12, 2019

Deane Morrison is a Science and Research Editor at the University of Minnesota.

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Star map March 2019 submitted by D.Morrison

Northern Sky: March 16-29, 2019

NORTHERN SKY – By Deane Morrison  

March 16-29 2019

We’re now deep into spring equinox time, when the sun climbs fastest through the northern sky. The equinox happens at 4:58 p.m. on March 20, and Grand Marais gains three minutes and 28 seconds of daylight per day for two weeks around that date. But Anchorage, Alaska gains five minutes and 44 seconds, while in Trondheim, Norway, they’re gaining six minutes and 19 seconds. Trondheim gets more than an hour of extra daylight just during the 10 days straddling the equinox.
 
These ultra-rapid changes shouldn’t be too surprising. For example, in Trondheim, the day length goes from about four and a half hours in December to about twenty and a half in June. When the day length has to increase that much in just six months, it’s going to change pretty fast. And it’s fastest in March because that’s when the sun moves northward most rapidly.
 
At the equinox, neither pole is pointing toward the sun, and the day length is the same, theoretically, all over the planet. We actually get slightly more than 12 hours of daylight on the equinoxes because Earth’s atmosphere is a gigantic lens that allows us to see the sun for a few minutes before it rises and after it sets.
 
The equinoxes are also times of switchover. During the winter, the farther north you go, the shorter the day length. After the spring equinox, it’s the other way around, and as you go north, the day length increases.
 
All this is due to Earth orbiting around the sun while being tilted on its axis. That tilt doesn’t change during the course of a year. The North Pole always points to the same spot in the sky, near the North Star, and it’s our orbital motion that makes it point toward or away from the sun, or neither, depending on Earth’s position.
 
If that’s hard to visualize, get an apple and face a wall. Tilt the apple a little so that the stem—the apple’s north pole—points somewhat upward and toward the wall. Then, without spinning or pivoting the apple in any way, move it counterclockwise in a circle and imagine the sun in the center. Move your arm horizontally, as if stirring a pot, keeping the apple pointed toward that same wall. When it’s closest to you, the apple tilts toward the sun, like Earth at the northern summer solstice. When it’s farthest from you, it tilts away from the sun. That’s the winter solstice. At the midway points it tilts neither toward nor away from the sun, and those are the equinoxes.
 
Okay. In the sky. Jupiter is well up in the south in the predawn hour, Saturn is much dimmer and off to the lower left of Jupiter, and Venus makes it over the eastern horizon just as the sun’s rays start to wash everything out. 
 
In the evening, Mars is still up in the west after nightfall. It’s been kind of lonely, but some visitors are on the way. The Pleiades star cluster and the bright star Aldebaran, the eye of Taurus, the bull, are moving closer to Mars every night. Best viewing starts the 22nd of March, at about 8:30 or 9 o’clock, when the sky will be dark but the moon won’t be up yet.
 
March’s full moon comes right after the equinox, at 8:43 p.m. on the 20th. The moon will be just a day past perigee, its closest approach to Earth in a lunar cycle, and that means we get our third supermoon in a row. This one rises over Grand Marais at 6:52 p.m., less than two hours before fullness, so it’ll come up very round as well as very big.
 

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Feb MNStarwatch.jpg

Northern Sky: February 16, 2019

NORTHERN SKY – Deane Morrison
February 16 – March 1, 2019

In the second half of February, most of the astronomical action is still in the morning sky.
 
Venus is heading toward the sunrise while Saturn is climbing up away from it. Between the 17th and the 19th, the two planets pass each other. They come closest on the 18th, when Saturn will be one degree, or two moon widths, below Venus, which is by far the brighter planet. For the rest of the month, the distance between them widens, and by March 1 they’ll be 10 degrees apart.
 
Saturn is following Jupiter, and now these two outer planets are rising earlier every day as they sail westward across the morning sky. Jupiter is brighter than Saturn, but in case you’re not sure which object is which, a fat crescent moon will be right above Jupiter on February 27th. A thinner crescent will be near Saturn on March 1, and Venus on March 2.
 
What makes the outer planets move westward across the sky—and the stars, too—is Earth’s orbital motion. But the outer planets’ own orbital motion makes them drift eastward with respect to the background of stars. Jupiter drifts eastward faster than Saturn, and now, that motion is carrying it toward Saturn. Late next year, Jupiter will pass Saturn—and very closely, which will be a lot of fun to watch. 
 
In the evening sky, Mars is still in the west after nightfall. It’s the vlodrdy of the outer planets, and moves the most rapidly eastward against the stars. It is dropping westward, but so slowly that it seems to be holding its own as the stars rush past it. Right now, that’s what the group of bright winter constellations is getting ready to do.
 
One of those constellations is Gemini, the twins. Its two brightest stars are Castor and Pollux, the heads of the twins. Gemini’s other stars are dimmer, but still, this constellation looks like what it’s supposed to be: two human figures. Pollux is lower and slightly brighter than Castor. Pollux is a large star with at least one large exoplanet, but Castor, not to be outdone, is a system of six stars. It has two main stars that orbit each other.
 
Each is a little bigger than the sun, and each has a small companion called a red dwarf star. And associated with this system is a pair of red dwarf stars that orbit each other and also appear to orbit the two main stars, albeit very slowly. Multistar systems are common, and needless to say, they can get complicated.
 
On the 16th, a bright waxing moon will be near the Gemini twins. Two nights later it’ll be near the backward question mark of stars that outlines the head of Leo, the lion. Early the next morning, at 3:03 a.m. on February 19th, the moon reaches perigee, its closest approach to Earth in this lunar cycle. Not quite seven hours later, it becomes full. Because it will be so close to us, this full moon qualifies as another supermoon, so it’ll be especially large and bright.
 
There’s just one little fly in the ointment, a common one when full moons come in the morning. On that day, the 19th, the moon sets over Grand Marais at 7:18 a.m.—a couple of hours before fullness. So if you want to see a supermoon at its biggest, roundest and brightest, go outside at least half an hour before moonset, which would mean by 6:45 a.m. And you’ll need a clear view of the western horizon. Or, if you’d rather watch a super moonrise, try the one right after full moon, on the evening of the 19th. It will still be pretty big and beautiful.
 

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