Venus Transit of the Century

With a plethora of websites dedicated to tomorrow's transit of Venus across the face of the Sun, including a page on Wikipedia about it, I don't feel the need to wax eloquent about the upcoming event in too much detail. Numerous sources can be read to learn about the orbits of Venus and Earth, the importance it once had in determining the distance scales of our solar system, and so on. However, since this blog is dedicated to the observer in the Oneonta, NY region, you're probably wondering about when it will be visible.

The most recent transit of Venus occurred in early June of 2004.  This transit occurred in the early morning in North America, with viewers in New York seeing it already in progress as the sun rose.  This made the event a bit of a challenge to see, since getting up before the sun rises isn't on most people's list of favorite things to do.  In Michigan at this time, I would have been an undergraduate at Central Michigan University.  Since I was an avid astronomer and astronomy student at the time, if it had been visible then I'm sure I would have gone to see it at our school's telescope.  The fact that I don't have any memories of it makes me think it may have been cloudy that day.

For those who don't know me...I have a terrible memory.  Case in point: I currently have 13 Post-it notes on my desk at this very moment with reminders for various things!  Not to mention the five half-page sized pieces of paper with other various notes jotted on them and an index card of notes as well.  But I digress...

The 2012 Venus is visible in North America in the early evening until sunset, making it much more accessible for the average viewer.  Expected to begin at approximately 6:00 p.m. in Oneonta, the second planet from the Sun (and our closest planetary neighbor) will continue its sojourn across our star's face until well after the sun has set, giving us only a limited opportunity to watch it for approximately an hour and a half.

The current weather forecast is for clouds and possibly rain.  If you're a sucker for "once-in-a-lifetime" opportunities, you may want to take a trip somewhere else to watch it - preferably farther west where you can watch it for a longer time period.

HOWEVER!  The Internet now offers the couch-astronomer and those of us in cloudy parts of the planet the chance to watch this event live as seen from somewhere else. You can visit the website for the SLOOH Space Camera or NASA's live webcast from Mauna Kea, Hawaii. I recommend tuning into the webcast shortly before 6:00 p.m. EDT to make sure you see it.  If you want it to feel like you're really there watching it through a telescope, get a paper towel tube and hold it up to your computer screen.  Who says you need fancy equipment?  The Internet is pretty fancy in my opinion!

If you are in the Oneonta area and the weather magically happens to be clear in the late afternoon on June 5, come see us at the SUNY Oneonta observatory at College Camp.  We will have a couple telescopes with solar filters for safe viewing set up.  Don't look directly at the sun for this event, or permanent eye damage may result.  We will have safe equipment for viewing the event.  Our viewing of the Sun and the eclipse will be open to the public starting at 5:30 p.m.

If the weather looks bad, hop online and visit one of the websites above.  This is what I did for the most recent annular solar eclipse and it wasn't bad.  Better than missing it altogether, anyway!

Happy viewing!

How to Buy a Telescope for Yourself

Throughout this blog I have made reference to viewing various celestial objects and events through binoculars or a telescope, and this works fairly well if you already own one or both such instruments. However, suppose you don't own either one - or, suppose you own a pair of binoculars but are itching to buy a telescope. It is perhaps the most common question that novice astronomers and non-astronomers ask experienced amateur and professional astronomers: "I'd like to purchase my first telescope. What telescope should I buy?" Today I will provide you with some instructions and advice that should (hopefully) be of use to you as you begin shopping around. In a future entry I will explain how to purchase a telescope for your child.

Before You Begin
If you are new to the night sky, then I would suggest buying a pair of nice binoculars first. You can drop $100 at Walmart for a cheap telescope that will quickly disappoint, or you can buy a quality pair of binoculars at the same cost that will provide better image quality. Yes, you are losing out on magnification (although don't buy the pitch from the cheap retail telescopes that claim 500X magnification!), but what you are gaining is an easily-transported, well-made optical instrument that will introduce you to the night sky before you get lost using a new telescope.

Here is a common scenario: you enthusiastically run to the store to buy a telescope, spend $150 on one that promises incredible magnification and comes in a box plastered with amazing images of planets, nebulae, and galaxies, then take it home and don't know what to look at. This occurs because the telescope didn't come with a drive motor or computerized paddle - you know you'd like to look at Saturn, but don't even know where Saturn is.  You go inside also wishing you knew what season the constellation Orion was visible, pack the telescope in its box, and it subsequently collects dust.

Is the best choice to go buy a nice computerized telescope?  Not unless you'd like to spend $500 or more on something that will likely sit in your garage or basement for the foreseeable future.  Buying a nice pair of binoculars and a star atlas allows you to fall in love with the night sky.  Go outside, lay on a blanket, and use your star atlas to guide you from star to star through a constellation.  Binoculars have sufficient magnification (the first number in the specs: for example, "7x50" binoculars have a magnifying power of 7X and an aperture of 50 mm) as to reveal rich open star clusters, the phases of Venus, the Galilean moons of Jupiter, and exquisite lunar features.  Star-hopping like this helps to familiarize yourself with the night sky.  Using star maps from an atlas or an astronomy magazine, you can become an expert in night-sky viewing.  Then go buy a telescope.

Types of Telescopes
There are several different kinds of telescopes that can be differentiated by the optical elements they utilize and the mounts on which they are built.

1. Refractors:  Refracting telescopes are long and narrow tubes with a glass lens on one end and an eyepiece on the other:
   
   These telescopes can be on equatorial mounts (shown above) or altitude-azimuth mounts (which are easier for pointing, harder for tracking).  Cheap models will have one simple lens at the aperture (the big end), while higher quality models will have a two-piece (achromatic) or three-piece (apochromatic) compound lens.  The more lenses, the better the image quality because these additional lenses are correcting for an effect called "chromatic aberration" where different colors are focused at different distances by the glass lens.  Of course, the more compound the lens, the higher the cost as well.  Many refractors are not motorized, although some of the high-end ones can be.
2. Reflectors:  Reflecting telescopes utilize mirrors to focus the light rather than an aperture lens:
   
   These can be long or short, and most often have an open aperture with a mirror on the lower end.  The light is reflected off this mirror to a smaller, flat mirror up near the opening and then directed out the side of the telescope through the eyepiece.  Reflectors do not have chromatic aberration and typically offer more bang for your buck as far as aperture size goes.  The larger the aperture, the more light is collected - producing a brighter image with better resolution.  Equatorial mount reflectors can come in both motorized and non-motorized forms.
3. Dobsonians:  Dobsonian telescopes are simply reflecting telescopes that sit on the ground in an altitude-azimuth mount:
   
   Other than this mount difference, they have the same characteristics as other reflectors while also providing much longer focal lengths - giving you higher magnification capabilities (provided you have the right eyepieces).  Dobsonians are almost never motorized, but many do come with a computer paddle that tells you which direction to move the telescope by hand.  This is a reasonable compromise between paying less for a non-motorized telescope while also having the advantage of a built-in object library.
4. Schmidt-Cassegrains: The final "general" category is the Schmidt-Cassegrain Telescope (SCT) that uses both a lens and mirrors to focus light:
   
   These provide great image quality, high magnification potential, and are usually computerized...but they are also expensive. 

Choosing a Telescope
When you are ready to purchase your first telescope, there are a number of factors that you should consider.  These factors are (in no particular order):

1. Budget
2. Optical quality / aperture size
3. Portability
4. Time available for use
5. Ease of use

Budget:  Most people consider budget the primary factor, and this is reasonable.  When buying a telescope, you can find them ranging in price from $100 to $10,000!  My first tip: don't run to a department store and buy that $100 one I mentioned earlier.  While affordable, these telescopes are mass-produced with low-quality optical elements and a wobbly mount.  Why does the mount matter?  If your telescope is constantly shaking and vibrating when you touch it and doesn't stay aimed at anything without drifting, your experience will be extremely disappointing.  Having a stable, sturdy mount is almost as important as having quality optics.  For your first telescope, plan on spending around $300-$400.  This will ensure that you have struck a good balance in quality and size for your first telescope.  Which brings me to the second factor...

Optical quality:  If the quality of the lens or mirrors in your telescope is poor, your viewing experience will be poor as well.  Department store telescopes are made with cheap glass lenses that offer more aberration than acclamation. A telescope retailer (either a store or online) will provide better quality options.  You want a telescope that uses quality lenses or mirrors!  This ties in with aperture size too.  In general, bigger is better.  However, bigger is also more expensive.  You'll need to strike a balance.  You can use a diagram like this to determine your optimal aperture size:

"Limiting stellar magnitude" in this diagram simply refers to the faintest object you can see through the telescope.  Larger numbers correspond to fainter objects.  Between 6-10 inches in aperture diameter typically provides a reasonable performance for its cost.  Refractors have smaller apertures than most reflectors, but can provide better images if you pay for it.  For reference, planets are bright, galaxies are faint.  Planets are easily visible in nearly all telescopes, while galaxies are only visible with larger apertures - typically greater than 10 inches.

Portability:  Will you be taking your telescope on trips, or will it always be used outside?  Will you be the one using it, or will your child?  Portability is an important thing to consider depending on your plans for the telescope.  Larger telescopes and sturdier mounts are heavier to move around and sometimes require a bit of dis-assembly to transport.  Additionally, if your telescope has a drive motor and/or computer it may require a source of electricity.

Time available for use:  How often do you envision the telescope being used?  Once a week?  Once a month?  Only once?  If you will use it a lot, you may wish to spend more on one that will provide a lifetime of viewing options - this generally means purchasing a larger telescope with a broad range of eyepieces.  If it will be used only on occasion, then don't spend more than $500.  If this might be used once or twice before interest in it wanes, don't spend more than $300.

Ease of use:  How good are you at learning to use new equipment?  Is this for a child or an adult?  Simple telescopes may look "too basic" but they are much easier to use than computerized telescopes.  They act as "point-and-shoot" telescopes, and all you really need to learn is how to point them using the axis knobs.  However, you also need to be familiar with the night sky.  Motorized, computerized telescopes make it very easy to find things...provided that you have it plugged in and set up properly and have done a correct alignment using several stars in the sky.  Motorized telescopes have thicker user manuals.

The Final Choice
After you have considered all these factors, it comes down to making a choice.  Many amateur astronomers will go with a 6- or 8-inch Dobsonian reflector and be very happy with it.  Others prefer to buy a nice 3- or 4-inch refractor and get superb views of solar system objects.  Motorized SCTs are extremely hard to find under $700 unless you buy one secondhand.  All things considered, I prefer to recommend getting as much aperture as you can afford.  A great 4-inch refractor is nice, but at the cost of something like that you can get a 12-inch reflecting telescope with a drive motor that will allow you to see many more types of objects than the smaller refractor.  Consider the factors I have mentioned above carefully, then talk to a telescope retailer to find one that will best fit your desires.

Resources
Check out some of these manufacturer websites to see your options and their costs:

• Meade
• Orion
• Celestron
• Galileo

Eclipse Update

After reviewing an interactive and animated web tool called Shadow & Substance, it appears that Oneonta may not get to experience even a partial solar eclipse on May 20 after all. It seems we are just a bit too far east. I had hoped that our altitude might help to override this, but it looks like that may not be the case. At any rate, this will not stop me, and should not stop YOU, from keeping an eye on the Sun as it approaches the horizon. Right at the point of sunset it may be possible to see the slightest piece of the Sun become obscured by the Moon. Try to find a place up in the hills that has a clear view of the western horizon (no trees). If you miss it, then wait until August 2017! There will be a partial solar eclipse visible from Oneonta for sure. Venus is beginning to set earlier and earlier in the evening now. It has passed its greatest elongation and is not heading down into the glare of the Sun. On June 5th it will transit in front of the Sun, with first contact occurring at about 6:10 p.m. EDT. I will write about this in more detail as the date gets closer. In the meantime, pray for clear skies!

Saturn is continuing to be a stunning sight through most telescopes. With its rings tilted at a 13-degree angle to our light of sight, they are easily spotted. During our most recent public observing night at College Camp, the air was still enough that even the Cassini division was visible in the 16-inch telescope, along with 4 moons (Titan, Tethys, Rhea, and Dione).

What a beautiful vision! Every person who views Saturn through a telescope when the seeing is good remarks how it looks just as if it were a picture held up at the other end of the telescope. Watch Saturn's moons from night to night to see how their positions change. The semester is coming to a conclusion this week, so I'm busy preparing reports and final grades. Once this has died down, I will be back with another post. Happy viewing!

Transits, eclipses, and meteors...oh my!

Ever since Venus and Jupiter made a wonderful pass by each other last month, Venus has been dominating the evening sky after sunset. Shining brilliantly in the western sky, Venus has passed its greatest eastern elongation (the point where it is farthest east of the Sun - visible in the evening) and is now on its way back into the sunset glow for the upcoming transit in front of the Sun on June 5th. This will be something nobody alive wants to miss, as the next one won't happen for another 105 years! Until then, we Oneonta residents will hope and pray for clear skies that day. For now, there are still some exciting things to come.

The United States is not often blessed with the opportunity to view a solar eclipse, but this month we will be...in part, anyway. An annular solar eclipse will be visible in the southwestern portion of our country on May 20.

If you live in New Mexico, Arizona, Utah, Nevada, or California (or will be there on vacation) you will get the chance to see the Moon almost block out the Sun completely. Annular eclipses happen when the Moon lines up perfectly with the Sun in our sky, but is at a point farther away in its orbit around the Earth than average. This results in the Moon having a slightly smaller angular size than the Sun, producing a ring of sunlight around the New Moon instead of being completely blocked out. While not quite as spectacular as seeing a total solar eclipse, annular eclipses are also amazing to watch and certainly, beggars can't be choosers!
Here in Oneonta, we will see a partial solar eclipse beginning around 5:15 p.m. on May 20 and continuing on until sunset. Even though we won't be able to see totality from our location on the Earth, I still plan on viewing this event if our skies are clear. If you plan on viewing the eclipse, be sure to use appropriate eye protection. I will probably use a telescope fitted with a solar filter. More on the eclipse as the date gets closer.

More immediately, we have another meteor shower coming up. On the night/morning of May 4th/5th, the Eta Aquarid meteor shower will be visible. This meteor shower is one of two that derive from the dusty trail of Halley's Comet (the other being the Orionids) and, while not a particularly active meteor shower, can produce 10-20 meteors per hour at its peak. While its radiant won't rise until the early hours before dawn on May 5th, it is usually better to look about 90 degrees away from the radiant anyway to see those dust particles that give us a glancing blow. Viewing after midnight is recommended, but unfortunately this year the Full Moon's overwhelming brightness may hinder attempts to see all but the brightest streaks across the sky. It's still worth a look, however. Additionally, since the maximum technically occurs during the Oneonta afternoon, if you are clouded out on the night of May 4th you can try again on the night of May 5th. Here is a chart showing the radiant of this meteor shower as it is rising in the early hours before dawn in early May:

Happy viewing!

Don't miss the Lyrid meteor shower

The coming of spring also marks the second significant meteor shower of the year - the Lyrids. Radiating from the constellation of Lyra, this moderately active meteor shower peaks on the evening of April 21st into the morning of the 22nd.

While the Moon has often been an unwelcome visitor during major meteor showers recently, this isn't the case this time. New Moon occurs on the 21st this month, meaning the Moon will set with the Sun. This leaves an entire moonless night of meteor viewing - although the activity will be limited until after midnight. Just as the front windshield of your car collects more rain droplets as you drive than does the rear windshield, once our local part of the Earth has rotated past midnight it becomes the leading face as the Earth moves forward in its orbit around the Sun.

This year's Lyrid meteor shower will likely produce around 20 meteors per hour, although there have been rare instances when the shower produces an outburst of over 50 per hour.

Meteor shower viewing can sometimes produce spectacular bursts of light that you'll remember for years to come. Other times, different causes can produce memorable stories. Several years ago as a graduate student, I headed out for a night of meteor viewing. Grabbing a cup of coffee from a 7-Eleven, I found a dirt road in the middle of farm land and pulled over. I then clambered onto the roof of my car, spread out a blanket, and laid down to watch the sky. Around 3 a.m., a truck slowly drove by my car, checking to see what I was up to. Because it had its headlights on, I closed my eyes to avoid losing my dark adapted vision. About 10 minutes later, a police car pulled up - apparently called by those people in the truck. After a brief chat with the officer and an explanation about the meteor shower happening over our heads, he went on his way - probably shaking his head at the silly young man laying on his car in the middle of the night in a corn field. That's a story I will never forget!

The night air this month will most likely be cold, so make sure you bundle up tight when you head outside. With any luck, there will be no snow on the ground so if you can find a dark location outside of town then bring a blanket and something hot to drink and set up camp to see what this year's Lyrid meteor shower has in store for us.

Happy viewing!

Beautiful Conjunction

Over the course of the nights of March 12 and 13, Venus and Jupiter gracefully passed by each other in the night sky. Only a few degrees separated the two bright planets, and it was truly a blessing to view this conjunction in Oneonta under remarkably clear skies.

Seen hovering above the 16-inch dome at College Camp in the image above (Venus on the right, Jupiter on the left), these two planets are the first points of light to appear out of the fading sunset. If you know where to look, they can even be spotted while the sun is still up - though it is admittedly difficult. Venus is approaching its greatest eastern elongation as it traverses its orbit out from behind the Sun, so while it proceeds to increase its apparent distance from the Sun for the time being, Jupiter will gradually move closer and closer to the Sun as our own planet travels onward. Ultimately, Jupiter will be lost as it passes behind the Sun, only to eventually make a reappearance in the pre-dawn sky.

Look carefully and you'll spot the Pleiades star cluster above and nearby (above the telescope in this image). Look for the two planets to be joined by a slender crescent Moon on March 25 and 26. This will be a lovely grouping not to be missed.

In addition, Mars is making its presence known for the entire night these days. Looking to the east, its ruddy hue is unmistakeable in the constellation of Leo.

Here it can be seen rising above the 14-inch telescope dome, glimmering brightly in the east. If you wait until around 10:00 p.m., you'll even catch Saturn as it rises near Spica in the constellation Virgo. Need help finding Spica? Find the Big Dipper, then follow the curve of the handle to "Arc to Arcturus" - that other really bright star on the northeastern horizon at this time of night. Then "Speed on to Spica", following the horizon toward due east. Here is a chart facing east to help you.

Arcturus is the star on the left, Spica is the star on the right, and Saturn is in between, closer to Spica. Enjoy viewing our neighbors in the solar system!

Can you spot the Space Station?

Identifying planets and stars is fun, and gazing upon nebulae and galaxies can be breathtaking, but you may find yourself at times looking for something more...transient. More challenging, perhaps. The planets shift positions almost imperceptibly from night to night, and the nebulae and galaxies don't seem to move at all, and while this makes them reliable targets when you need to find them, they may provide less of a "thrill of the hunt" once you know where they are and have seen them a couple times. Is there anything in the heavens that isn't permanent?

One easy answer to this is: satellites! A mere 55 years ago, mankind launched the first artificial satellite (Russia's Sputnik) into orbit around the Earth and since then we have put thousands more up there.

While only a few hundred or so are currently functioning, there remain many that are still visible from Earth...if you know where to look.

Amateur ham radio operators often use the radio signals emitted by many satellites to track them through the sky. However, some are bright enough to see with the naked eye - and many can produce bright "flares" where their apparent brightness suddenly increases by many factors for several tens of seconds.

Brightest of them all is the International Space Station (ISS).

Adorned with over twenty double-sided solar panels, the space station has so many reflective surfaces that when it is visible it can often be one of the brightest objects in the sky. Furthermore, taking just 90 minutes to orbit the Earth, many people are surprised by how quickly it moves across the sky.

There are several Internet engines that can help you keep track of satellites as they orbit. Visit www.n2yo.com and you will be greeted with a Google Maps-based image that shows real-time locations of a number of prominent satellites, including the ISS. If you are looking for help predicting when they will be visible from your location, check out Satellite Flybys, where rise times, brightnesses, maximum elevations, and directions on where to look are given. For example, using this website I have found that for the Oneonta area the ISS will be visible for the next few nights:

Date	Rise time	Direction to look	Transit time	Max. Elevation	Magnitude
02/16/2012	05:58:44 p.m.	WSW	06:01:51 p.m.	87 deg.	-4.0
02/17/2012	06:38:41 p.m.	W	06:40:57 p.m.	28 deg.	-2.1
02/18/2012	05:45:23 p.m.	NNE	05:46:31 p.m.	37 deg.	-2.7

Finally, the website Heavens-Above gives the same information for satellites while also providing Finder Charts for other celestial objects like planets, comets, asteroids, etc.

While the ISS is quite bright, most other satellites are a bit fainter. They may be easily mistaken for airplanes, but rather than blinking these satellites will be a constant brightness because they are being illuminated by the sun rather than any mounted light bulbs. Look carefully and you will see them moving against the background stars.

Happy hunting!