FAQs about the UNH Observatory

About the Observatory...

Who works at the UNH Observatory?

The UNH Observatory is run by a Manager, usually a Physics graduate or undergraduate student, and staffed by a host of volunteers that include, current and former UNH students (both Physics and non-Physics) and local amateur astronomers. If you live in the Seacoast area and are interested in amateur astronomy, love telescopes, or would like to learn more, you might want to consider volunteering at the UNH Observatory. We are always looking for new dedicated staff members, of all levels of knowledge and experience; for more information, email us at unh.observer@unh.edu.


How powerful is this telescope?

Well, that's actually a more complicated question than one might expect. Many people, when they ask this question, want to know how many times an image is magnified when you view it through the telescope, as compared to when you view it with your naked eye. If this is what you're interested in, the magnification can range from 122.2x with our 32mm eyepiece, to over 400x with our 8mm eyepiece. However, the eyepieces generally used for public and private sessions give 122.2x (32mm) and 78x (50mm) magnification.

For astronomers, however, magnification is less important than light gathering power. The more light a telescope can gather, the fainter the objects that one can view with it. Magnification is nice, it makes it easier to see details of objects, but without sufficient light gathering power, the nebulae, and galaxies that we're interested in observing, will be too faint to see.

The light gathering power of a telescope is determined by the diameter of its primary or objective mirror. Telescopes are basically light buckets, the wider they are in diameter, the more light they can collect, and therefore the fainter the objects are that we'll be able to see. Our telescope is 14 inches (355 mm) in diameter. As the light leaves the telescope's eyepiece at the spot where the image comes into focus (known as the exit pupil), it is about 7 mm in diameter, so the telescope's primary mirror is about 50 times wider (350mm/7mm) than the exit pupil. That means that the mirror has 2500 times more surface area than the exit pupil (50 x 50). So, using our 14 inch telescope, we'll be able see objects that are 2500 times fainter than we would with our naked eye. This means that we should be able to use this telescope to see objects that are about 14th magnitude.

Magnitude is a measure of how bright a star appears when seen from Earth. It is related to how much energy is leaving the star as visible light and to how far the star is away from Earth. The smaller the magnitude, the brighter the star. The brightest star in the sky other than the Sun is Sirius, which appears to be -1 magnitude. The faintest stars that a human eye can see on the clearest night are 6th magnitude; there are thus 7 magnitudes between them. The stars at the limit for observing through our telescope are thus slightly fainter compared to the faintest ones we can see as those stars are to Sirius.

This assumes though, that we are looking through a vacuum, which we are not. Air currents in the atmosphere and scattered light from street lamps, nearby cities, and sometimes the moon, brighten the background of the sky and limit how faint the objects are which we will be able to see. Since we are fairly close to sea level, there's a lot of atmosphere and moisture to look through, and since we're on campus, albeit at the edge, there's a significant amount of light from nearby buildings and street lamps as well. I usually have success with spotting objects which are brighter than 8.5th magnitude and have been able to spot on occasion objects nearly as dim as 10th. Since the light from these objects, usually nebulae or galaxies, is spread out and not concentrated at a point, like a star, I expect that the dimmest stars that I see on those nights are between 10th and 12th magnitude. The Keck telescopes in Hawaii, which are 10 meters in diameter, can detect stars at about 22nd or 23rd magnitude.

How old is the telescope and how much did it cost?

We don't have a concrete answer for this one. The manual for the telescope is for a 1981 model, but the best history we can uncover seems to indicate that it was donated to the university around 1984, costing then around $11,000. Online reviews of a comparable 1990's model price such a scope in the $6,000 range today. You can get a good idea about how much telescopes go for nowadays by looking at the advertisements in such magazines as Sky and Telescope or Astronomy.

What kind of research has this telescope been used for?

The UNH Physics department uses this obsesrvatory strictly for educational purposes. In addition to the public and private viewing session that we offer, students in PHYS 405/406- Introduction to Modern Astronomy, and of the introductory astrophysics class are brought out to the observatory at least once a term (there are many sections, so this can take the entire term). Students in the introductory class then must write a laboratory report about the telescope and the objects that they see.

While it might be possible to do some rudimentary research with a telescope this size, these days it is more of a 'scope for a dedicated amateur. Such amateur astronomers are noted for spotting new comets and asteroids. The High Energy Astrophysics Group research group here does do astrophysical research, but uses a telescope (COMPTEL) on an orbiting satellite - the Gamma Ray Observatory. Unlike the Hubble Space Telescope, COMPTEL looks at light that is of much higher energy, and therefore of much higher frequency than we can see directly with our eyes.

About astronomy...

I'm a parent whose child is super interested in Astronomy, but I'm afraid I'm a bit out of my league here. What can I do?

Don't worry! This is without a doubt one of the most common questions we get at the Observatory. And I mean, really who can blame your child for finding outer space so fascinating? The first thing to do is support your child's excitement about the subject. Imagination, creativity, and wonder are as a big an aspect of astronomy as physics and math are and you definitely don't ever want to stifle those qualities in your child. Astronomy is also a great family activity, so this may be a perfect opportunity for you and your child to spend some quality time together. The New Hampshire Space Grant Consortium even has an Astronomy Road Trip that highlights over 20 astronomy-related places you and your child can visit right in here in the Granite State!

You don't need to rush out and buy a telescope right away (unless you really want to!). There are plenty of free telescopes in the area in addition to the UNH Observatory that have free public viewings, specifically the McAuliffe-Shepard Discovery Center in Concord and the Museum of Science in Boston. A better place to start is just learning the stars and constellations with your child. Getting yourself a good resource, like H.A. Rey's The Stars, would be a good start, but there are plenty of books on amateur astronomy and constellations. After that, you might want to try a digital planetarium software like Stellarium. Stellarium is as powerful/useful as the more professional astronomy software and it's free; in fact, you can even use it to control a telescope if you wanted to. 

Of course, how much farther you'd like to go beyond that is entirely up to you and your child. As always, feel free to contact us at the UNH Observatory if you have specific questions.

I want to be an astronomer, what should I do?

Well, first off, everyone can be amateur astronomers. All that it takes is looking up at the sky on a clear night and liking what you see. Try using binoculars as well and look at the Moon. The next thing you'll want to do and to continue to do is read. Read a lot. If you want to learn more about the names of the stars and constellations and a bit about how they appear to move through the sky , try a book by H. A. Rey (the author of the Curious George books) called The Stars. You'll also want to pick up some of the astronomy magazines out there. Younger readers will appreciate Odyssey, whereas older readers will find Astronomyor Sky and Telescopeto be excellent magazines all three of which cover current events in astronomy as well as present articles giving background information on various astronomy topics. Most larger bookstores and most libraries will have an astronomy section, and the web is an excellent source as well. There is probably an amateur astronomy association in your area; these organizations are great groups to get together with to talk about astronomy and to have a chance to look through other people's telescopes.

Professional astronomy is mostly a specialty for physicists, but it also overlaps with earth sciences and mathematics. If you want to become a professional astronomer, or at least have a more in depth appreciation for what they do, you'll want to take as many math and science classes as you can in high school, particularly the advanced math and physics classes. If you are more interested in planets and the moon than in stars, galaxies, nebulae, and what not, then you'll want to look for colleges that have strong geophysics, or meterology programs. They may even have a program that is called "planetary science" (MIT, CalTech, Univ. of Colorado at Boulder, Brown, and U. of Arizona do) or one that offers astronomy as a degree separate from physics. If you are more interested in stars, galaxies, quasars, and cosmology, you want to look for colleges with strong astronomy groups within their physics departments or even with a separate astrophysics group. UNH has a gamma-ray astrophysics group, a solar-terrestrial theory group, and a space science group within our physics and earth, oceans and space departments. Once you are in college, try to get involved with research as a part time or summer job. They don't expect you to know everything right away, but it is a great learning experience.

How Far? How large? How long ago?

A few notes: Planetary (and lunar) radii are given in terms of Earth radii (the Earth's radius is 6,378.1 km at sea level at the equator.) Planetary distances are given in astronomical units (AU), where one AU is the average distance from the sun to the earth (which is about 93 million miles or 150 million km). Distances outside the solar system are measured in light years (ly), the distance light travels in a year, (which is 63,000 AU, 9.5 trillion km, 6 trillion miles).

ObjectHow far?How large?How long ago (was it formed)?
Moon250,000 miles; 400,000 km0.272 earth radii4.55 billion years
Mars1.5 AU0.532 earth radii4.55 billion years
Jupiter5.2 AU11.2 earth radii4.55 billion years
Saturn9.5 AU9.449 earth radii4.55 billion years
Sirius8.6 ly  
Procyon11.4 ly  
Altair16.8 ly  
Vega25.3 ly  
Spica262 ly  
M45, Pleiades380 ly less than 100 million years
Betelgeuse428 ly  
Polaris431 ly  
M44, Praesepe ("manger"), aka Beehive cluster577 ly  
Stars in the constellation Orion (besides Betelgeuse)over 700 ly 2-12 million years
Saiph722 ly  
Rigel773 ly  
Almitak818 ly  
Mintaka916 ly  
M27, Dumbell Nebula1,250 ly2 ly diameter 
M42, Orion Nebula1600 ly15 ly diameter 
M57, Ring Nebula4100 ly 20,000 years ago
M17, Omega Nebula5000-6000 ly  
M8, Lagoon Nebula5800 ly  
M1, Crab Nebula6300 ly10 ly x 15 ly, center ~4.4 ly diameter1054 C.E.
M13, Great Globular Cluster in Hercules22,800 ly200 ly diameter 
M3 globular cluster30,600 ly  
M31, The Andromeda Galaxy2.9 (2.2?) million ly120,000 ly diameter 
M322.9 (2.2?) million ly8000 ly diameter 
M81, Bode's Galaxy12 (10.5?) million ly100,000 ly 
M82, Cigar Galaxy12 (10.5?) million lysmaller than M81 
M65, one of Leo triplet of galaxies35 million ly  
M66, one of Leo triplet of galaxies35 million ly  
M51, Whirlpool Galaxy37 (20?) million ly65,000 ly diameter

Data for this table was obtained from Dixon's Dynamic Astronomy, Karl Kuhn's In Quest of the Universe, Galaxies by Timothy Ferris, the Hipparcos catalog sample pages, and the SEDS Messier Object page. The data did not always agree between sources.

What about meteor showers?

On any given night, if you go out to a dark sky and watch the stars, you'll be able to see about one meteor streak by per hour as a piece of rock enters the atmosphere and burns up. During meteor showers however, one can see as many as 50 to 100 per hour.* We see these showers when the Earth crosses the path of debris left behind from a comet. Because we cross a number of the same paths year after year in the same direction, meteors from indivdual showers appear to come from the same spot in the sky each year and are named after the constellation that that spot is in. The paths that these meteors take, can cross the entire sky and the spot that they radiate from is also fairly large. This makes observing meteor showers something that you wouldn't want to do with a telescope. The field of view is so small that you'd miss most of the show. A better way to see a meteor shower is to find a dark clearing away from city lights, lie down and look up at the sky. For more information on meteor showers see Sky and Telescope's meteor page.

Other objects that are better seen with the naked eye include human-made sattellites including the International Space Station (ISS). These also appear in the sky too briefly and move to fast to easily catch in the telescope, generally crossing the entire sky in a few minutes. The Human Space Flight page will tell you where & when to look for the Space Shuttle and the ISS.
* Some years, if the source comet may have dumped more debris into the section of its orbit that we cross, in which case we might catch a meteor storm of 500 to 2000 meteors per hour!

Why is the sky so bright at night?

Part of the reason the sky around our observatory can get fairly bright is because of the lighting around campus. Much of the light, along Mast Road, Main St. and A-lot as well as some of the fields occasionally in use, is directed not only toward the ground it is intended to illuminate, but also up into the air. Whether it goes there directly, or is reflected off the ground, the light then scatters around off of dust and moisture in the the atmosphere, brightening the sky. The full moon does this as well, and we see quite a bit of bright sky showing up on nights when it is out. We tend to schedule public nights for times when the moon won't be out so that we can still see the dimmer objects.

For the most part, the campus lights are there for additional security and I don't have a problem with that (although some folks will argue that increased lighting actually promotes crime activity and/or gives folks a false sense of security - see the International Dark-Sky Association site below for more details). The lights we have on campus could be more efficiently designed and shielded though, to send light more to where it is intended. Since refitting the lights with more efficient fixtures, while in the long run may be more economical, in the short term is probably a bit pricy, the observatory uses a quick fix. We have a "Sky-glow" filter which blocks out those lines in the spectrum coming from Mercury and Sodium lamps. It works best in screening out light from low-pressure Sodium lamps but enhances the contrast noticibly even from the high-pressure kind and the mercury ones we use. We can't do anything about the moon though beyond scheduling most of our open nights for times when the moon is not out. Light from incandescent bulbs can't be easily screened out either.

Sky-glow is yet another reason why most major observatories are located high up in the mountains, or in the case of the Hubble Space Telescope, out in orbit. When you are above much (or all) of the atmosphere, there's much less of an effect of light scattered about - there are fewer particles to scatter off of.

For additional information on light polution see the Interational Dark-Sky Association, Turning Day Into Night: Facts about Light Pollution or if you're interested in how serious the problem is around you, check out a map pertaining to light polution found on our Clear Sky Clock Site.