What’s Up in the Sky – October, 2013

Eagles and Dolphins and Swans, Oh My!

If you are reading this, you probably know about the Summer Triangle. Vega, Deneb, and Altair make up this asterism which is almost directly overhead and visible all month. Let’s take a look at some of the mythology surrounding these constellations and then see how we can use them as guides to cool stuff.

Face south. Look up. Better yet, lie down on a lawn chair. You will see a triangle of stars standing on its point. The brightest, Vega (VEE-ga), is in the constellation Lyra (the Lyre), which appears as a small equilateral triangle attached to a parallelogram below it. The lyre, a small, stringed instrument like a little harp, was by some accounts, invented by the god Hermes. He gave it to his half-brother Apollo, who passed it along to Orpheus, his son. So talented on the instrument was Orpheus that he was able to use it to charm Pluto and the guardians of the underworld to allow his wife, Eurydice, the victim of a viper bite, to return with him to earth. Of course, there were conditions: he would have to walk ahead of her and was not look back until they had both returned to the upper world. You can probably guess how that turned out.

At the top left of the triangle is Deneb, the tail of Cygnus, the Swan, and at the bottom is Altair, in the constellation Aquilla, the Eagle. The swan is usually depicted as flying down the Milky Way toward the horizon while the eagle is seen as flying in the opposite direction.

According to legend, Aquilla was the bird of Zeus and when the king of the gods needed an errand run between heaven and earth, he called on Aquilla. The bird was rewarded for his loyal service with a place among the stars.

Between the swan and the eagle are two little constellations that are fun to learn. Look right above Altair for a small group of four stars. This is Sagitta, the Arrow, and is sometimes described as having been shot at the eagle by Sagittarius, the Archer (luckily it missed). Sometimes the arrow is shown in Aquilla’s talons and other times it is associated with Cupid’s arrow.

Just to the left of Sagitta is one of my personal favorites, Delphinus, the Dolphin. It looks like a little diamond of stars with a tail. There is an interesting story about two of the stars in this constellation, Sualocin and Rotanev. The names were first published in a star catalogue compiled at the Palermo (Italy) observatory in 1814. Turns out that if you reverse the spelling you get Nicholaus Venator, an assistant astronomer at the observatory!

I guess that’s one way to get you name up in the sky.

This month in history:
Oct. 1: NASA founded – 1958
Oct. 5: Robert Goddard born – 1882
Oct. 8: MESSENGER spacecraft makes second flyby of Mercury – 2008
Oct. 14: Chuck Yeager breaks sound barrier – 1947
Oct. 22: First record of solar eclipse – 2136 BCE
Oct. 30: STS-61A Challenger Space Shuttle launched – 1985

What’s Up in the Sky – September, 2013

Plenty of Planets for September

September opens with what I would consider a spectacular display for binoculars. Unfortunately, you have to be out at 6 a.m. to see it so I think I will begin today’s column with an excellent sight that will be easy to see.

On Sunday, September 8, right after sunset (about 8 p.m.), go down to Kollen Park, out to Holland State Park, or anywhere else with a clear view of the western horizon, and look for a thin, crescent Moon. Just to its right, about two Moon diameters away, will be Venus – a truly spectacular sight. To the upper left of this pair you will spot the planet Saturn, a good target for a small telescope. In fact, this gathering is a splendid opportunity to do some great observing with binoculars or a small scope.

If the 8th is a wash, you can still see a nice Moon-Venus-Saturn get-together on the 9th, but the Moon will be over on the other side of Saturn, not nearly as cool. But if you continue to observe the two planets from night to night, you will see them get closer and closer until the 18th when they appear nearest each other.

So what about this 6 a.m. thing? Set your alarm next Sunday and look toward the east an hour before sunrise. The bright “star” you see is actually the planet Jupiter and it forms an isosceles triangle with the stars Castor and Pollux, which lie to its left. Below this group you will see the crescent Moon at the top of another isosceles triangle, this one short and wide. The base of this trio is formed by the planet Mars on the left and the star Procyon on the right.

This activity has the added benefit of you becoming familiar with that part of the predawn sky so you can observe an upcoming event of great coolness. This would be Mars passing in front of a distant star cluster.

At the first opportunity, use binoculars or a small telescope to locate Mars and scan down and slightly left until you come to a small cluster of stars (not visible to the naked eye). This is called M44, the Beehive cluster, and is 500 light years away. If you are really motivated, observe the planet each clear morning and on September 8 and 9 you will see Mars “among” the stars of M44 and its daily motion will become apparent. This is a very cool, very memorable observation that is well worth the effort.

Whether it’s before sunrise or after sunset, there will be planets up in the sky.

This month in history:
Sept. 3: Last two Apollo Moon landings canceled by NASA – 1970
Sept. 6: Space Shuttle Challenger makes first night landing – 1983
Sept. 15: “Lost in Space” premieres – 1965
Sept. 20: Wernher von Braun arrives in US – 1945
Sept. 24: John Young, first Space Shuttle commander, is born – 1930
Sept. 29: First satellite launch from Alaska – 2001

What’s Up in the Sky – August, 2013

August is always a good month for observing and next month is doubly so. I have two challenges for dedicated readers. First,, observe the Perseid meteor shower for at least two hours, and second, find at least three double stars.

As with any meteor shower, the best viewing occurs in the hours just before dawn, but most people prefer an earlier viewing experience. My advice is to take a nap after dinner Sunday, August 11, so you can set up your lawn chair, bundle up in a sleeping bag, and sit back and enjoy the show starting around midnight. No optical aid (such as a telescope) is required or even desirable – this is a naked-eye observation. Depending on how clear and dark your sky is, you could see up to 50 or 60 meteors per hour. Don’t get discouraged if you only see a few at first. The rate should increase as time goes on and your eyes become dark-adapted.

Start your double star search with Mizar, the middle star in the handle of the Big Dipper, found in the northwest sky around 10 p.m. Look closely and you will notice Mizar has a faint companion, known as Alcor. In a small telescope you can see what was first observed in 1650 – Mizar itself is a double star, its two components close, but easily separated.

In contrast, it was not until 1889 that astronomers, using a spectroscope, discovered that Mizar’s brighter component consisted of two stars, making it the first binary to be discovered by spectroscopic methods. Years later the other component was also shown to be a spectroscopic binary, making Mizar a quadruple star.

I used to teach that Alcor and Mizar make up what is known as a visual double. That is, they are not gravitationally bound to each other, but merely lie almost in the same direction of sight and therefore appear close to each other. In 2009 researchers reported strong evidence indicating that not only was Alcor also a spectroscopic binary, but also that it is indeed gravitationally bound to the Mizar system. So, when you look at the famous double in the handle of the Big Dipper, you are actually looking at six stars. How cool is that?

Next check out the star at the very bottom of the Northern Cross and the one right next to Vega (called Epsilon Lyrae). These are both nearly overhead and thus perfect for a small Dobsonian telescope. I will let you discover how cool these guys are.

All in all, this should be a good month to enjoy what’s up in the sky.

This month in history:
August 2: First televised liftoff of lunar module – Apollo 15’s “Falcon” – 1971
August 5: Neil Armstrong born – 1930
August 12: Echo 1 launched – 1960
August 20: Voyager 2 launched – 1977
August 25: Voyager 2 flies past Saturn – 1981
August 27: Teacher in space program announced – 1984

What’s Up in the Sky – July, 2013

Stars, Of Course

I feel sorry for stars. After all, when it comes to astronomy, they should be the stars of the show, so to speak. When people see me loading my telescope into the car they will often ask if I’m going out looking at the stars. In fact many amateur astronomers are affectionately referred to as “stargazers”.

But the truth of the matter is we hardly ever use the telescope to look at individual stars. We observe star clusters, exploded stars, and double stars, but through a telescope, most stars look the same with slight variations in color and vast differences in brightness, both of which can be seen with the naked eye.

That’s why I think the fun of looking at the stars lies in knowing what you are looking at. And this month’s sky has quite the variety.

There are a number of internet videos comparing the sizes of stars, but that’s just the beginning. For example, facing east, locate the Summer Triangle formed by the stars Vega, Deneb and Altair Deneb, the star farthest to the north (left), is sixty thousand times as luminous as the sun, which is why it’s a good thing it’s sixteen hundred light years away. In fact, its enormous intrinsic brightness makes it one of the most remote stars visible to the naked eye.

The star at the top of the triangle, Vega, appears to be the brightest, but is only about sixty times as luminous as the Sun. It appears bright because it’s close – a mere 25 light years away. So there’s your lesson in apparent vs absolute brightness:: Nearby Vega only appears bright but far distant Deneb is absolutely a thousand times brighter.

Deneb is also very large, about two hundred times the diameter of the sun. But the biggest star in our sky is Antares, in the constellation Scorpius. With a diameter almost nine hundred times that of the Sun, if it were located at the center of our solar system, its outer surface would extend beyond the orbit of Mars!

Remember last month’s brightest star, Arcturus, the trivia question answer? Though not as big as Antares, it is an orange giant whose color can easily be seen. To the naked eye it appears slightly reddish, but if you view it through a telescope slightly out of focus, its color is more apparent.

Arcturus has a large proper motion, or sideways drift across the sky. And it is not moving in the general direction of most stars in the disc of our galaxy, but is actually cutting perpendicularly through it.
So you see, this month there are more than just fireworks up in the sky.

This month in history:
July 4: Deep impact collides with comet – 2005
July 7: Mars rover, Opportunity is launched – 2003
July 10: First transatlantic TV signals made possible by launch of Telstar – 1962
July 18: India launches its own satellite, becoming the seventh nation to do so – 1980
July 20: Humans walk on Moon for the first time – 1969
July 28: First photo of total solar eclipse – 1851

What’s Up in the Sky – June, 2013

A Variety of Sights in June’s Sky

After the last Ice Age, Africa’s Sahara desert was green and fertile and the climate supported an abundance of wildlife that attracted huntsmen, and later herdsmen. These people recorded scenes of life in rock paintings of great beauty. Surely, while tending their flocks under pristine skies with diamond stars, they looked to the heavens and saw herdsmen.

One of springtime’s best constellations, Bootes (boo-OH-teez), is often depicted as a herdsman and is easily found this time of year. Find the Big Dipper high in the southwest and follow the arc of the handle away from the bowl down to the bright star Arcturus (“follow the arc to Arcturus”). Above it lie five stars in the shape of a leaning house which, along with Arcturus, form the main body of the constellation.

The name “Arcturus” means guardian of the bear so we have a herdsman driving a bear (Ursa Major) through the sky. I guess a bear is more exciting than a cow. Arcturus is also notable for being the first star to be observed in the daylight with a telescope. And that was in 1635.

Scenes such as those depicted in the Saharan rock paintings suggest that Bootes is one of the oldest constellations and was even mentioned in Homer’s Odyssey of the 8th century B.C.

Now look just to the east (left) of Bootes for a circlet of stars forming a small bowl. This is Corona Borealis, the Northern Crown. Another ancient constellation, it was known to the Arabs as a broken dish, the Greeks called it a wreath, and to the Australian aborigines it represented a boomerang.

Corona Borealis is associated with a number of mythological legends. It was once known as the Crown of Ariadne, the heroine who saved Theseus from the minotaur in the maze on Crete. Later she married the god Bacchus who had given her a magnificent jeweled crown. When she died, he honored her by putting her crown in the heavens.

The brightest star in the constellation, Gemma, Latin for “gem”. It is also sometimes known as “Alphecca” which is derived from an Arabic root meaning “broken” perhaps referring to the broken ring of stars.

Then there is T Corona, also called the Blaze Star. Normally inconspicuous at magnitude 10, in 1866 and again in 1946 it flared up to be as bright as Gemma. We call such stars “recurrent novae”.

So, from a herdsman driving a bear to a crown of jewels, there is much to enjoy up in the sky.