STAR GAZER
THE INTERNATIONAL EDITION
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Dean: Hey there stargazers. I'm Dean Regas, outreach
astronomer for the Cincinnati Observatory, and I'll be your guide
to the sky this month on Star Gazer. After the grand finale of
a glorious fireworks show, stay up a little later to watch the
heavenly star show. I'd like to share with you the many beautiful
celestial objects you can observe in the warm summer evenings.
In fact, you can spend an entire night on just two constellations
- Scorpius the scorpion and Sagittarius the Centaur. These two
zodiacal constellations huddle close together in the southern
sky and are easy to recognize by their shapes and relatively bright
stars. Here, let me show you
Okay, we've got out skies set up for early July, looking south at 11 pm. Scorpius is one of the few constellations that actually looks like its namesake. You won't need to strain your imagination to see a scorpion in these stars. Scorpius is visible above the southern horizon as a long fishhook shape. This curve of stars marks the scorpion's tail and stinger. You need more imagination to see the body, heart, and claws of the scorpion, but the stars in this region tie together so nicely. As the night moves on, the scorpion appears to crawl from left to right, or westward, along the southern horizon. The brightest star in Scorpius is a beautiful red star named Antares. The brilliant tint of this star has inspired observers for thousands of years. Antares means "Rival of Mars" because of its similar hue to the red planet.
But it's nothing like Mars. Antares is one of the largest known stars in the galaxy. Look at the entire orbit of Mars would fit inside Antares. But at around 600 light years away, it's still about the same brightness as the much closer and much smaller planet Mars. With its flickering red light, Antares looks like it's the beating heart of the sinuous scorpion.
But watch out for his stinger! At the end of the hook you'll spy two stars that are almost on top of each other. The brighter one is called Shaula and the dimmer one is Lesath. Together they were known as, "the sting" in ancient Arabic and are the brightest stars to appear so close together in the night sky.
In mythology, Scorpius is the slayer of the mighty Orion. It took just one sting to fell the great hunter and send him to the underworld. Legend has it that Orion never wanted to see that darned scorpion again - and they're never visible at the same time.
Orion presides over the winter sky while Scorpius reigns over the summer. Binocular alert! Just above "the sting" are two open star clusters just at the edge of 20/20 vision. These clusters are called M6 and M7 (the "M" stands for the inventor of this catalog system, Charles Messier). Even with the weakest binoculars, both clusters make a beautiful sight. M7 is also called Ptolemy's Cluster since he wrote about the nebulosity of this region almost 2000 years ago. M6 is nicknamed the Butterfly Cluster because the stars resemble outstretched wings. As the night rolls on and we get closer to midnight you'll notice someone hunting the great scorpion - but it's not Orion out for revenge. Just to the left of the scorpion stands Sagittarius the Centaur Archer who has his bow firmly aimed at Antares. Sagittarius is recognizable more as a teapot-shape than an archer. The spout of the teapot marks the bow and arrow and the dipper shape forms his body. Most myths equate Sagittarius with a centaur named Chiron. His prized students included Achilles, Jason, and Hercules, all of whom, I guess, didn't mind being taught by a half man, half horse.
When you look at Sagittarius, you are looking into the center of our galaxy, the Milky Way. If you're observing from an extremely dark sky site, you will see the cloudy band of the Milky Way stretch across the sky from north to south ending in Sagittarius. This also makes a great place to look with binoculars. The Milky way is really "billions and billions" of stars. Better than the best fireworks show the stars of Scorpius and Sagittarius will make you say ooh and aah all summer long. Remember, to keep looking up.
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Dean: After the fireworks this week stay up
a little later to watch the grande finale in the heavens. Two
zodiacal constellations huddle close together in the southern
sky, Scorpius and Sagittarius, and I can show you where to find
them. Right this way...
Okay, we've got out skies set to early July, looking south at
11 pm. Scorpius resembles a letter "J" while Sagittarius
looks more like a teapot. The brightest star in Scorpius is bright
red Antares. It's often called the heart of the scorpion with
its flickering red light beating ominously in the night sky. Just
to the left of the scorpion stands Sagittarius the centaur archer.
Sagittarius is supposed to be a centaur - half man, half horse
- who has his bow firmly aimed at Antares. As the night goes on,
watch the archer chase the scorpion across the southern horizon.
This is Dean Regas from the Cincinnati Observatory reminding you
to keep looking up!
How did you like this episode?
Please give us your comments. (Click
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* This week's Sky At A Glance and
Planet Roundup from Sky & Telescope.
This week's Sky At A Glance displays current week only.
Starry Night Deluxe was used to produce this episode
of Star Gazer
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Dean: Hey there stargazers. I'm Dean Regas, outreach astronomer for the Cincinnati Observatory, and I'll be your guide to the sky this month on Star Gazer. July is quite a month for planet viewing either at sunset or sunrise. Let me show you.
O.K., I've got our skies set up for about an hour after sunset Monday July 18. Look low in the west just as it gets dark and you'll be able to see the elusive planet Mercury hovering above the western horizon. It will be in about the same position for all of next week. Up to Mercury's left is Regulus, the bright blue star which marks the heart of Leo the Lion. A hook of stars marks the lion's head and mane and a triangle of stars up to the left marks where his hindquarters would be. The brightest star in the triangle is named Denebola and the word Denebola actually means 'the tail of the lion'.
Let's go forward in time a bit and you'll see that each night Regulus and Leo will drop a bit lower and Mercury will shift a bit farther to the left and seem to approach Regulus. They won't be very high above the horizon so you'll have to hit the timing just right. Look too early and it'll be too bright to see them and if you look too late Mercury and Regulus will be too low to see. And next week is the best time to look for them.
Much easier to find and not so picky about the time is the ringed planet Saturn. Look up and to the left of the tail of Leo for a pair of lights close together in the night sky and you've found the ringed planet Saturn and the star Porrima, its temporary companion. Saturn is a great target for a small telescope and if you watch for the rest of the summer you'll be able to see Saturn leave Porrima behind and get closer to Spica, the bright star off to Saturn's left. Saturn and Spica are nearly the same brightness now but Saturn will get a bit brighter each week throughout the summer months.
Now for those of us who have to get up before dawn there are a few planets for us to enjoy also. This is an equal opportunity sky. About an hour before sunrise next Monday look low in the east and you'll see there are a load of bright stars over there. The brightest is not a star, it is a planet, the biggest one in our solar system, Jupiter. Jupiter will be far and away the brightest thing you'll see over there in the east until the Moon joins them in a week or so but we'll talk about the Moon a bit later. Jupiter is also a great target for a small telescope or even with binoculars because Jupiter is really, really big. It's eleven times wider than our 8,000 mile wide Earth. Plus it has 4 Moons that you can see with only a pair of 7 x 50 binoculars. They move around Jupiter fairly quickly and you can actually see them move in the course of an hour or so.
On Saturday July 23rd the last quarter Moon
will be about 7 degrees above Jupiter and the next day the 24th
an even skinnier Moon will be 7 degrees to the left of Jupiter.
This is a great chance to see how much of the sky the Moon crosses
every day. Let's go back to Monday again and look well down to
the left of Jupiter and look for a pattern of stars that has always
looked like a big fang to me. The two brightest stars in this
fang are Capella in the constellation Auriga and Aldebaran in
Taurus the Bull. The other stars have names as well but the best
part of this fang is the point made up by the sharp 'v' of stars
in the head of Taurus the Bull. Officially these are two constellations
but to my mind they should be seen as a huge fang from a celestial
sabertooth tiger stalking the predawn skies. Just below the fang
look for a reddish point of light. It's the small red planet Mars
and Mars is about as dim as it gets right now because it's very
far away from Earth on the other side of the solar system. So
now is not the best time for viewing Mars. It will be a lot better
in March of 2012 when Mars will be much closer and twice as bright
as it is now. So that's Mercury, Regulus and Saturn in the evening
and Mars, the Fang and Jupiter in the morning. Keep looking up!
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Dean: This is quite a month for planet viewing.
You have lots to see at sunset or sunrise. Here let me show you.
I've got our skies set up for about an hour after sunset Monday
July 18. Look low in the west and you'll be able to see the elusive
planet Mercury hovering above the western horizon. Up to Mercury's
left is Regulus the heart of Leo the Lion. Look beyond the tail
of Leo for a pair of stars close together in the night sky and
you've found the ringed planet Saturn. The bright star off to
Saturn's left is Spica. About an hour before sunrise next Monday
look in the east and you'll see a planet, the biggest one in our
solar system, Jupiter. Down to the left of Jupiter, look for a
reddish point of light. It's the small red planet Mars. So that's
Mercury, Regulus and Saturn in the evening and Mars and Jupiter
in the morning. Keep looking up!
Please give us your comments. (Click
Here)
* This week's Sky At A Glance and
Planet Roundup from Sky & Telescope.Starry Night Deluxe was used to produce this episode
of Star Gazer
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Dean: Hey there stargazers. I'm Dean Regas, Outreach
Astronomer for the Cincinnati Observatory, and I'll be your guide
to the sky this month on Star Gazer. Next week after it gets good
and dark out the three wonderfully bright stars of the Summer
Triangle ride high in the heavens. And although they look like
they are all the same to the naked eye nothing could be farther
from the truth. Let me show you.
O.K., we've got our skies set up for the last two weeks of July around 10 p.m. facing east. Look way up high in the east, not far from overhead, where you'll see three bright stars, the brightest of which is the first point in the Summer Triangle, and the closest to overhead, Vega, the fifth brightest star in the entire sky shining at what astronomers call 0 magnitude which makes it roughly 2 1/2 times brighter than the other two bright stars of the Summer Triangle, the first magnitude stars Altair and Deneb. And if you connect these three very bright stars with lines you'll see where the name Summer Triangle comes from.
Now each star is the brightest star of the constellation to which it belongs. Vega belongs to the constellation Lyra the Harp. Altair is the brightest star of Aquila the Eagle and Deneb is the bright tail star of Cygnus the Swan. We can learn a lot about how bright and how far away stars really are just looking at these three. You'd think that Vega, since it is the brightest, is the closest but it's not. Vega is so far away it takes its light 25 years to reach us. Which is why we say Vega is 25 light years away. It is almost 1/3 farther away than dimmer Altair, which is the closest of the three at only 17 light years away, which means we see the light that left it only 17 years ago.
So why is Vega so much brighter? Simple. Vega is a much bigger and much hotter star than Altair. Compared to our almost one million mile wide Sun, Vega is almost 2 and 1/2 times as wide, whereas Altair is only one and 1/3 times the width of our sun. So next time you're out with friends star gazing, if someone in your group is 17 years old you'll be able to say, "Hey, look at Altair. We're seeing the light tonight that left Altair when you were born." and if someone in your group is 25 years old simply say, "Hey look at Vega. The light we're seeing tonight is the light that left it during the year you were born." Kind of a nifty way to time travel huh?
But what about Deneb, which is only slightly dimmer than the closest of the three, Altair? Well it is a whopping 1500 light years away, which again means we are now seeing the light that left it 1500 years ago. So if Deneb is almost as bright as 17 light year away Altair it must be a much, much bigger and brighter star and it is. Deneb is a whopping 116 times the diameter of our Sun. This means that Deneb is as much wider than the Sun as our Sun is wider than the Earth. Wow!
In fact, as astronomer Fred Schaaf puts it, Deneb releases as much light in one night as our Sun does in a century. And if Deneb were as close as Vega it would be as bright as a crescent Moon. How bright is that? Well go out the morning of July 25th and see for yourself. A beautiful waning crescent Moon will be in the eastern sky before dawn for you to enjoy. On the 25th it will be about half way between Jupiter and Mars. The next day the 26th a skinnier Moon will be just above Aldebaran the red eye of Taurus the Bull. And the next day Wednesday the 27th an even skinnier Moon will make a beautiful sight as it passes between the tips of the horns of Taurus and will be only 3 degrees away from the red planet Mars.
So get out next week and look for the three
bright stars of the Summer Triangle: Vega, Altair and Deneb riding
high in the east. And in the morning watch the waning crescent
Moon pass between the horns of Taurus as the Moon approaches Mars.
It's fascinating plus it's fun! Keep looking up!
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Dean: The three bright stars of the Summer Triangle
ride high at the end of July. Look high up in the east around
10 p.m. and you'll see three bright stars Vega, Altair and Deneb
which if connected make a very nice triangle. Although they look
almost alike they certainly are not. Vega the brightest is actually
farther away, 25 light years, than dimmer and closer 17 light
year away Altair. Vega looks brighter because it is a much bigger,
hotter star, 2 1/2 times as wide as our Sun whereas Altair is
only 1 1/3 times as wide. Deneb the dimmest is so far away it
takes its light 1500 years to reach us. But it is so huge it releases
as much light in one night as our Sun does in a century. Deneb
is as much wider than our Sun as the Sun is wider than the Earth!
Wow! I'm Dean Regas from the Cincinnati Observatory, keep looking
up!
How did you like this episode?
Please give us your comments. (Click
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* This week's Sky At A Glance and
Planet Roundup from Sky & Telescope.Starry Night Deluxe was used to produce this episode
of Star Gazer|
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Dean: Hey there stargazers. I'm Dean Regas, Outreach Astronomer
for the Cincinnati Observatory, and I'll be your guide to the
galaxy this month on Star Gazer. How many times have you seen
the Milky Way? Only on those rare occasions when I'm far away
from the city lights can I see that beautiful streak of stars
glowing in the night sky. As an astronomer in Cincinnati, the
only Milky Way I see is filled with chocolate and nougat. Where
did the Milky Way go? In larger cities, light pollution is becoming
a big problem. City lights illuminate signs, parking lots, buildings,
and also the night sky. The more light that we shine up, the
less star light we see shining down. Even though it's invisible
from cities, I'll share a sneaky tip to find the Milky Way in
your sky. Let me show you.
Okay, let's pretend we're far from city lights and looking at the summer sky. You'd see so many stars - you couldn't count 'em all. A band of faint light stretches from the northeast to the southwest. This is the Milky Way. Most ancient cultures were just as fascinated with the Milky Way as they were with any planet or constellation. When you see the Milky Way, you are looking at billions and billions of stars. This is where most of the stars in our galaxy can be found. There are so many stars in our line of sight that they appear as milky clouds. Some bright and famous constellations can be found along this galactic river such as Cassiopeia the Queen, and Cygnus the Swan. Cassiopeia is one of the most recognizable constellations. In the summer evenings, she sits on her throne in the northeast sky but in the shape of a "W". If you're imagination-challenged, you may have a difficult time picturing a queen among these stars. I like to think of the "W" shape as her crown sparkling with stellar jewels.
High in the east you'll see three very bright stars marking the Summer Triangle. The Summer Triangle is not an official constellation - it's a star pattern we call an asterism and it's made of three bright stars from three different constellations: Lyra the Harp, Cygnus the Swan, and Aquila the Eagle. Let's focus in on Cygnus since it's probably the easiest to identify because of its cross-like shape. In fact it's also called the Northern Cross. Cygnus' brightest star is Deneb, which marks the tail of the swan. Cygnus is located in an extremely rich part of the Milky Way and is thought to be flying along the river in the sky. Near Deneb, the Milky Way branches into two channels leaving a dark region in the middle. This is called the Cygnus rift or the Northern Coal Sack. In the south, the Milky Way threads between two zodiacal constellations, Scorpius and Sagittarius. The scorpion is easy to identify with its bright red star for a heart and curved tail and stinger. The stars in Sagittarius resemble more of a teapot than an archer. But both can be found low in the southern sky every clear summer evening.
When you're looking between Scorpius and Sagittarius,
you're looking into the center of our galaxy. Astronomers believe
that in the center of the Milky Way lies a massive black hole.
X-ray satellites have recently taken some amazing pictures of
this mysterious region called Sagittarius A. Now, of course you
can't see the Milky Way if you're a city star gazer. Let's show
the difference between a rural sky full of stars and a light polluted
sky. Even though the Milky Way disappears, we still have some
constellations clearly visible, Sagittarius and and Scorpius low
in the south, Cassiopeia in the northeast and Cygnus high in
the east. So that's where the Milky Way is - even if you can't
see it. And my favorite summertime observing aids are binoculars.
Once you identify Cassiopeia, Cygnus, or Scorpius scan these
regions of the sky with your binoculars. With a little magnification,
a wealth of stars will be revealed to you. So start counting
those billions and billions of stars tonight and keep looking
up!
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Dean: Can't see the Milky Way where you live?
Let's take a trip to the country to see the river of stars.
Follow me...
Boy it's dark out here. A band of faint light stretches from
the northeast to the southwest, this is what we earthlings see
of the Milky Way, the main part of our galaxy - billions and billions
of stars. In front of this band of stars, you'll find Cassiopeia
the queen - the one shaped like a "W" - sitting in the
northeast. Cygnus the Swan, often called the Northern Cross,
flies through an especially rich part of the Milky Way high in
the east. So that's where the Milky Way is - even if you can't
see it where you live. So peer deeply and aim some binoculars
at these regions to find more stars than you could ever count.
I'm Dean Regas from the Cincinnati Observatory reminding you
to keep looking up!
How did you like this episode?
Please give us your comments. (Click
Here)
* This week's Sky At A Glance and
Planet Roundup from Sky & Telescope.Starry Night Deluxe was used to produce this episode
of Star Gazer
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