[ FirstLight Astronomy Club ] The Skies Above

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Morning Planets, Milky Way

The Galaxy >

The happening heavenly hot spots in the coming weeks aren’t up in the sky so much as they are around the edges.

Those visible planets which got all the hot press a couple weeks ago are officially finished with their alignment. They’re tanned and rested and preparing to make public appearances again.

A couple of them are opting to show themselves in the morning twilight to those of us who are early to rise - very, very early to rise...

Earth’s trek around the sun has now put us in such a position that the very distant cousins, Jupiter and Saturn, are on the morning (west) side of the sun. For people up this early a glance toward our eastern horizon about a half hour before sunrise will reveal one very bright “star” - Jupiter - and his dimmer but very close companion - Saturn. Watch them over the next couple months as they rise earlier and earlier and earlier.

Mercury, the closest planet to the sun, continues its forever breakneck sprint around the sun and appears on the eastern side of the sun, the sunset side. Look for a tiny, dim, star-like critter following the sun down into the horizon.

Because Mercury is in such a hurry - its “year” being only 88 days long - you’ll only have the next couple of weeks to catch it. After that the little guy will bolt in front of the sun again and disappear into the glare.

Where’s bright and shiny Venus? Being the second planet out, Venus isn’t in as much of a hurry to orbit the sun as Mercury. Right now she is behind the sun and won’t move out far enough to be seen until late summer, when she will again claim “evening star” status.

The most magnificent horizon hugger now in our evening skies is the Milky Way itself; the great band of light which later, during summertime, will stretch across the skies overhead from horizon to horizon. What is the Milky Way, you may ask? Good question!

Our sun is just one of over 100 billion stars held in a gigantic, spiral disk of stars more than 700,000 trillion miles wide. This is the galaxy we call home. We are looking at that monstrous, star-soaked disk edge-on when we observe the Milky Way.

Because it’s around the horizon in the evening, don’t bother looking for it; viewing any sky object along the horizon is very difficult at best. But as the night progresses the great band will swing over us like a celestial jumprope until by 4 AM it will be directly overhead.

By looking straight up in the sky during the early evening, when the Milky Way still circles us roundabout, you are looking up to the stars that are, more or less, traveling with us in our 260 million year orbit around the center of the galaxy. They are fellow pilgrims in our grand journey. Sadly, none of those stars you see will circumnavigate the galaxy even once. But that’s a sad star story for another day.

Images and movies of the planets and the Milky Way are waiting for you at http://firstlightastro.com/icolumn.html

Until next time, clear skies!

First week of June: AM - Jupiter & Saturn

First week June: PM - Mercury

Milky Way movie: how it moves through the night (390K)

Posted by Administrator at 2000.05.28 09:33 AM | Comments (0)

The Big Dipper

Observing >

One of the most easily found constellations in the northern skies is Ursa Major - the Big Bear. It’s so easy to find because inside Ursa Major is the well-known Big Dipper.

There are seven stars that make up the Dipper. (There are helpful star maps for this whole article at http://firstlightastro.com/icolumn.html.) With the exception of the stars on both ends, the Dipper is an “association,” astrospeak for a group of stars which were born at about the same time out of the same cloud and are also traveling in the same general direction. The stars on the Dipper’s end are not going with this flow; they are actually tens of trillions of miles farther away and moving in different directions. Because of the roaming about of all these stars the Dipper won’t look like a Dipper in 100,000 years. By then, if you’re around, it may be called The Big Tire Tread on the Side of the Freeway.

The stars that make up the leading edge of the “scooper” part of the Dipper are Merak and Dubhe. These are the Pointer Stars that most kids learn about in grade school pointing the way to Polaris, the North Star.

Dubhe, the more northern of the Pointer Sisters, has a secret. It’s a massive old star 60 times bigger than our sun, but a closer binocular look will reveal a tiny bluish companion star. These two are revolving around each other taking a mere 600,000 years to complete one revolution.

But wait, there’s more to Dubhe and its buddy than meets the eye! As astronomers studied the light from these two, it came to light that both of them had tinier - and very close - companions of their own. Thus, what appears as Dubhe, the star at the pour spout of the Dipper, is really a four-star system.

But Dubhe and friends are hardly the only stars out there with mates.

The second star from the end of the handle of the Dipper is a star system that is out of this world. Peering closely at them you may see a bright star named Mizar and a dimmer one called Alcor. Spotting that dim one was an eye test used by several peoples including the Romans and some native American tribes. But the fun is just beginning...

Grab some good binoculars and you’ll see a second star right next to Mizar. This is Mizar’s binary buddy, affectionately christened Mizar B. The stellar friendship between Mizar A and B was first discovered in 1650 by Italian astronomer Giovanni Battista Riccioli. It was the first discovery of literally tens of thousands involving stars with companions. It turns out our bachelor star, the sun, is in the minority.

This couldn’t be better for us.

If you need a planet that can support life order up one bachelor star exactly like the sun. Those stars with companions can’t hold onto a planet with a stable orbit. So as intriguing as they are, multiple-star systems are best seen at a distance - a great big distance.

One more thing about Mizar. Not only are Mizar A and Mizar B going around each other but it appears that Alcor itself is revolving around the Mizars! Want more? Each of those stars has another unseen star orbiting them! Why, Mizar and Alcor are hosting a six-star square dance!

Until next time, clear skies!

Posted by Administrator at 2000.05.14 09:36 AM | Comments (0)



Looking for something?	« April 2000 \| Main \| June 2000 » Morning Planets, Milky Way The Galaxy > The happening heavenly hot spots in the coming weeks aren’t up in the sky so much as they are around the edges. Those visible planets which got all the hot press a couple weeks ago are officially finished with their alignment. They’re tanned and rested and preparing to make public appearances again. A couple of them are opting to show themselves in the morning twilight to those of us who are early to rise - very, very early to rise... Earth’s trek around the sun has now put us in such a position that the very distant cousins, Jupiter and Saturn, are on the morning (west) side of the sun. For people up this early a glance toward our eastern horizon about a half hour before sunrise will reveal one very bright “star” - Jupiter - and his dimmer but very close companion - Saturn. Watch them over the next couple months as they rise earlier and earlier and earlier. Mercury, the closest planet to the sun, continues its forever breakneck sprint around the sun and appears on the eastern side of the sun, the sunset side. Look for a tiny, dim, star-like critter following the sun down into the horizon. Because Mercury is in such a hurry - its “year” being only 88 days long - you’ll only have the next couple of weeks to catch it. After that the little guy will bolt in front of the sun again and disappear into the glare. Where’s bright and shiny Venus? Being the second planet out, Venus isn’t in as much of a hurry to orbit the sun as Mercury. Right now she is behind the sun and won’t move out far enough to be seen until late summer, when she will again claim “evening star” status. The most magnificent horizon hugger now in our evening skies is the Milky Way itself; the great band of light which later, during summertime, will stretch across the skies overhead from horizon to horizon. What is the Milky Way, you may ask? Good question! Our sun is just one of over 100 billion stars held in a gigantic, spiral disk of stars more than 700,000 trillion miles wide. This is the galaxy we call home. We are looking at that monstrous, star-soaked disk edge-on when we observe the Milky Way. Because it’s around the horizon in the evening, don’t bother looking for it; viewing any sky object along the horizon is very difficult at best. But as the night progresses the great band will swing over us like a celestial jumprope until by 4 AM it will be directly overhead. By looking straight up in the sky during the early evening, when the Milky Way still circles us roundabout, you are looking up to the stars that are, more or less, traveling with us in our 260 million year orbit around the center of the galaxy. They are fellow pilgrims in our grand journey. Sadly, none of those stars you see will circumnavigate the galaxy even once. But that’s a sad star story for another day. Images and movies of the planets and the Milky Way are waiting for you at http://firstlightastro.com/icolumn.html Until next time, clear skies! First week of June: AM - Jupiter & Saturn First week June: PM - Mercury Milky Way movie: how it moves through the night (390K) Posted by Administrator at 2000.05.28 09:33 AM \| Comments (0) The Big Dipper Observing > One of the most easily found constellations in the northern skies is Ursa Major - the Big Bear. It’s so easy to find because inside Ursa Major is the well-known Big Dipper. There are seven stars that make up the Dipper. (There are helpful star maps for this whole article at http://firstlightastro.com/icolumn.html.) With the exception of the stars on both ends, the Dipper is an “association,” astrospeak for a group of stars which were born at about the same time out of the same cloud and are also traveling in the same general direction. The stars on the Dipper’s end are not going with this flow; they are actually tens of trillions of miles farther away and moving in different directions. Because of the roaming about of all these stars the Dipper won’t look like a Dipper in 100,000 years. By then, if you’re around, it may be called The Big Tire Tread on the Side of the Freeway. The stars that make up the leading edge of the “scooper” part of the Dipper are Merak and Dubhe. These are the Pointer Stars that most kids learn about in grade school pointing the way to Polaris, the North Star. Dubhe, the more northern of the Pointer Sisters, has a secret. It’s a massive old star 60 times bigger than our sun, but a closer binocular look will reveal a tiny bluish companion star. These two are revolving around each other taking a mere 600,000 years to complete one revolution. But wait, there’s more to Dubhe and its buddy than meets the eye! As astronomers studied the light from these two, it came to light that both of them had tinier - and very close - companions of their own. Thus, what appears as Dubhe, the star at the pour spout of the Dipper, is really a four-star system. But Dubhe and friends are hardly the only stars out there with mates. The second star from the end of the handle of the Dipper is a star system that is out of this world. Peering closely at them you may see a bright star named Mizar and a dimmer one called Alcor. Spotting that dim one was an eye test used by several peoples including the Romans and some native American tribes. But the fun is just beginning... Grab some good binoculars and you’ll see a second star right next to Mizar. This is Mizar’s binary buddy, affectionately christened Mizar B. The stellar friendship between Mizar A and B was first discovered in 1650 by Italian astronomer Giovanni Battista Riccioli. It was the first discovery of literally tens of thousands involving stars with companions. It turns out our bachelor star, the sun, is in the minority. This couldn’t be better for us. If you need a planet that can support life order up one bachelor star exactly like the sun. Those stars with companions can’t hold onto a planet with a stable orbit. So as intriguing as they are, multiple-star systems are best seen at a distance - a great big distance. One more thing about Mizar. Not only are Mizar A and Mizar B going around each other but it appears that Alcor itself is revolving around the Mizars! Want more? Each of those stars has another unseen star orbiting them! Why, Mizar and Alcor are hosting a six-star square dance! Until next time, clear skies! Posted by Administrator at 2000.05.14 09:36 AM \| Comments (0)
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