Report for 2001-06-08
Welcome to the Utah Skies Report.
Brought to you from beautiful Park City, "View-tah".
Lunar
Phase
| The moon is a few days past full. As such it
will be rising a couple of hours after sundown sundown and staying up
until just past sunrise.
The moon will dominate the nighttime sky. Only the planets can withstand
its overwhelming brightness. I watched Mars and the full moon rising
together the other night. It was an interesting pair. I took several
pictures of this combination. Hopefully these will come out ok and I can
add them to the Utah Skies website.
Try to make it a point to get out and observe the moon as people have done for centuries. It presents a significant amount of detail even to the naked eye. If you have binoculars or a telescope, you can spend a considerable amount of time exploring its craters and other prominent features. |
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| Sunrise: 5:56 am | Sunset: 8:56 pm |
| Astronomical Twilight Ends: 3:51 am | Astronomical Twilight Begins: 11:01 pm |
| Moonrise: 11:30 pm | Moonset: 8:05 pm |
The Space Station
The International Space Station will make a solo
pass over Park City this weekend. Saturday night, at 12:16, the ISS will rise in
the north west. It will then take about 10 minutes to cross the sky, setting in
the east. Unfortunately, the ISS will not fly directly overhead. Instead, it
will stay relatively low over the northern horizon - never getting more than 23
degrees above the horizon. Still, with this weekends beautiful weather
forecast, it should be pretty easy to find. At a visual magnitude of -1,
the ISS is brighter than any of the stars in the sky. Check it out!
Astronomy 101
In our last lesson, we spoke about stars and the
distance to the nearest star. Lets broaden our horizon a bit. This week, we'll
focus on our galaxy. "A galaxy is a massive system of stars, gas, and dark
matter held together by its own gravity". Up until very recently, it was
thought that the Milky Way Galaxy, our home galaxy, was the entire universe. The
advent of larger, more powerful telescopes and the use of cameras to record
images has pushed the frontiers of the universe well beyond the boundaries of
our galaxy.
With that said, let me make a statement. Every star that you see in the sky is
located within our galaxy. The vast majority are within a few thousand light
years. Thousands of light years you may be wondering? Within our galaxy? Yup.
Recent estimates place the diameter of our galaxy at around 120,000 light years.
Yikes! That's big! In other words, it takes light 120,000 years to cross our
galaxy. We are talking immense. 120,000 (light years) * 6,250,000,000,000(miles
per light year) = 750,000,000,000,000,000 miles in diameter. That's 75 with 16
zeros. 750 Quadrillion miles. That's even bigger than the federal deficit :)
Like I said before, these distances defy our ability to even conceptualize them.
We are taking HUGE here. And we're still within the bounds of our own galaxy!
The universe is estimated to contain BILLIONS of galaxies! We'll move out
of our galaxy in a future discussion.
Ok... back to our Milky Way galaxy. Current estimates place the number of stars
in our galaxy in the billions. Billions of stars = Billions of suns... Hmmmm....
There are many different types of objects in our galaxy. We have visited stars
and planets and nebulas and star clusters in previous reports. Each of these has
its place in the sky.
Ok... Enough science class... Let's get out and do some observing!
Planetary Report
| Mars is rising in the southeast around 9:30pm. Mars
has grown to 20". This is very near the maximum it will achieve on
this pass of the Earth. By the way, this is the largest Mars has appeared in over a decade! Mars has also brightened to
almost magnitude -2.3 making it by far the
brightest star-like object in the night sky. As I've mentioned previously, this combination of increased brightness and increased size is providing us with some of the best views of Mars in over a decade. I again got some spectacular views of Mars earlier this week. The details on the planets surface were impressive. If you own a telescope, or know someone who does, take it out and use it. Objects like Mars are quite impressive visually and really easy to look at with a telescope. The moon and the planets are ideal places to begin your astronomical journey. Mars reaches its Zenith, or highest point in the sky, around 1:30am. Best views of the planet start around 11:00pm. |
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This Hubble Space Telescope image shows Mars at various
points in its rotation. Use these views as guidelines to help identify the
features which you are able to see. |
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Venus is rising in the east about 3:45am. While it has dimmed slightly to about magnitude -4.3, it is still by far the brightest star-like object in the sky. Personally, I think Venus is most impressive as a naked eye subject. Telescopically, it reveals little detail beyond its shape. Venus is currently sporting a crescent shape. If you watch in over a period several weeks, you will get a chance to see it go from crescent to full and back to crescent. The image at right, which reveals substantial surface detail, was taken using radar. |
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| Take this bit of planetary information
either as an interesting side note, or an observing challenge. Pluto is in
the constellation Ophiuchus, about 15 degrees north of Mars. At magnitude
13.75, Pluto is basically out of reach of smaller telescopes. One way to
verify that you have found Pluto is to sketch the star patterns over
several nights. If you have actually found Pluto, one of the the faint
star-like objects will have moved over the course of a few nights. This is
Pluto. Pluto orbits the Sun at about 30 times the distance of the Earth - nearly 2.75 billion miles away. The image at right is one of the best ground based images I have ever seen so don't expect to see any surface detail. Merely seeing Pluto is an accomplishment. |
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Telescope Talk
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Contrary to the advertisements of many
cheap telescopes, the primary function of a telescope is not to magnify
objects. Nope. The primary function of a telescope is to gather light.
Most telescopic objects are extremely faint - beyond the ability of our
unaided eye to see. We use telescopes to collect larger amounts of light
and bring it to focus for us. With that said, if you want to see more and
fainter objects, you need a larger telescope. A larger telescope will
always produce brighter images, with greater detail, than a smaller
telescope. A quick formula to compare the light gathering power of
telescopes is to simply compare the squares of the aperture. So... a
4" will result in a light gathering factor of 16 (4*4), while a
5" will result in a light gathering factor of 25 (5*5). So. While the
5" is only 25% larger than the 4", it will collect 50% more
light. This is quite valuable when searching for those faint fuzzies. Utah
Skies is fortunate to have a large aperture telescope. Affectionately
called the ObDob, this 25" Dobsonian Reflector was built last year by
Obsession Telescopes of Wisconsin. A quick run of the numbers reveals a
light gathering factor of 625 (25*25). So... This scope is 5 times larger
than the 5" mentioned earlier, yet it collects 25 times more light!
This will take you several magnitudes deeper, enabling you to see details
which the smaller scope could never hope to see. These big scopes are definitely not for everybody. As you can see from the picture, these scopes are a handful. They require more space to store, are considerably harder to transport, and generally require a bit more physical effort than many people are willing to muster. If however, you want to search out distant galaxies, or see additional details in many of your favorite objects, there simply is no substitute for aperture. The image at right of M13,The Hercules Globular Cluster, was a major factor in my decision to purchase such a monster. As you can clearly see, each increase in aperture reveals additional details previously only imaginable. |
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Constellation Report
Our Constellation report is an easy way for people to become familiar
with the nighttime sky. We’ll discuss myths associated with the various
constellations as well as describing the numerous deep sky objects residing
in the area. No equipment is required to view the constellations, though
a star chart can be quite helpful. This ease of observing makes constellations
a natural place to begin your journey to the stars.
This weekend we’ll focus on the constellation Bootes,
pronounced (boo-OH-teez). Bootes is the celestial herdsman. He is anchored by
Arcturus, the brightest star in the northern sky. To find Arcturus, return to
the handle of the Big Dipper. Remember the saying: "Follow the arc to
Arcturus". The name Bootes is mentioned in Homer's Odyssey back in the 8th
century B.C.
Deep Sky Report
The focus of our efforts this week will be the deep sky objects of
Bootes.
| First off, lets take a look at Arcturus itself.
At mag -0.04, Arcturus is the brightest star in the northern sky. Arcturus
is only 37 light years away. It is also quite large at about 23 times the
diameter of the sun and radiating130 times as much energy. Looking at
Arcturus, you'll notice an orangish glow.
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| Moving on, we come Epsilon Bootis or Izar. This magnitude 2.35 star is actually a tight double star. The primary star is orange while the secondary shows a slight bluish/greenish hue. With a separation of only 2.8 seconds of arc, splitting this double will require a telescope. |
If you are able to find this object, you may be one of the few, the proud, the Deep Sky Obsessed. E-mail your findings to DeepSkyObservations@UtahSkies.org. |
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Check out our updated light pollution section. In it, you'll find ways to cut your outdoor lighting bill dramatically. At the same time, you'll be helping to preserve our environment. While you're there, use our new, automated e-mail generator to send an e-mail to your government officials. Tell them that you want to see them move Utah to the forefront in combating wasteful light pollution. |
Next Weeks Report
Next week, we'll continue our journey through the cosmos
and focus on the constellation Serpens Caput..
Closing
This "Star Cast" has been presented by Utah Skies. View-tah’s Astronomy Home. Utah Skies can be found on the World Wide Web
at http://www.UtahSkies.org. Visit
our site and discover the cosmos. While you're there, sign up to receive the free,
fully illustrated Utah Skies Report. Many of our up coming star parties will only
be announced to people on our e-mailing list. Sign up today.
