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Posts tagged ‘astronomy’

Assembling the Orion SkyQuest XT8i Intelliscope Dobsonian Telescope – Part 1

A bit of a disclaimer here. This is going to be as much of ‘what’s wrong with the Intelliscope’s instructions as much as it will be a  ‘how to’ for helping set-up your Intelliscope.

005First a little background: Dobsonian telescopes, with their large mirrors and lazy-susan bases have been around for ages but it wasn’t until Orion released their SkyQuest XT line in the late 90’s that they became popular. Previous Dobsonian telescope models had issues with balance and were trick to keep on target.  Odd solutions like weights added to the outside of the telescope were clunky and awkward for basic users. Orion solved the issue by adding the CorrectTension system, which was a spring that held the optical tube of the Dobsonian to the base. It was a simple and elegant solution and it worked very well. The line got excellent marks and was considered one of the best Dobsonian lines on the market . At first Orion just sold a 6″ and 8″ model, then added a 10″ model, a 4.5″ kid’s model, and later a 12″ model.

For several years, Orion pretty much dominated the Dobsonian Market, but when imitators cropped up they decided to improve their classic Dobsonian by adding a computer guidance system (not a computer control system like many GoTo telescopes). Here you would get the advantages of having a computer system to help you find objects. It would not require batteries for any motors and the observer would be the person moving the telescope, using a hand controller to guide them.

The whole system using a pair of magnetic encoders, and development was tricky. The initial plan was to have the Intelliscope completely replace the original Dobsonian line where it would be sold with and without the controllers. This didn’t happen due to some development issues. Once the Intelliscope was ready it was sold both with and without the controllers, but after a few years it was sold strictly with the Intelliscope controller system. This unfortunately left some ‘development scars’  that will show up from time to time as we assemble the telescope. (more…)

Astronomy Tips: Astronomy Smart Phone Apps Part 2

OK, so in Part 1 we covered 4 different astronomy/telescope apps for your Smart Phone.  In part 2? Well, we’re going to pretty much do some more of that.

ZoomCalc

ZoomCalc

ZoomCalc is a simple program where you can input stats from your telescope to get some interesting optical information about your telescope. The program has 2 parts, 1 for your telescope and one for the eyepieces. The first you need to enter the aperture, focal length, and eyepiece size (1.25″ or 2″). ZoomCalc then presents a screen of information about what your telescope can deliver:

Zoomcalc1

Sorry, the only screenshot we could find was in Cyrillic. But suffice it to say you are provided with 12 optical aspects of the telescope from Maximum magnification, aperture ratio, and many others. If you don’t know what the terms mean there is a handy pop-up button that gives you a definition. Mind you all of these results be be had with a calculator but its handy to get them all at one shot.

The eyepiece part is a bit useless. It just calculates magnification, something anyone should be able to do with a calculator or in their head. An app like this should have gone the extra step and figured out apparent fields of view and such. It would have been much more useful.

Verdict: Handy for experienced astronomer, but not critical

Next Up: Telescope Calculator Lite

telescopecalclite

This is a lot like Zoom Calc but does both more and less in the same time. With Telscope Calc Lite you enter your telescope’s aperture, focal length and the eyepeice’s focal length and apparent field. From this Telesceop Calc gives you some handy calculations:

telescopecalclite1

There is more about fields of view and such with this app, but unlike ZoomCalc there is no explanation of the terms. The help pages gives some hints but not a true definition. This is designed for astronomers who already have knowledge of such terms and just would rather have an easy way of calculating rather than trying to remember the formula for true field.

Telescope Calc Lite has a nice night mode you can toggle from the menu. Handy.  The ‘Pro’ version of this app costs $0.99 and lets you save values you have entered.

Verdict: Handy for astronomers with some experience.

Next: Meteor Show App for Android

meteorshower

Meteor Shower App is pretty straight forward. You open it up and it shows you  a list of all the major meteor showers for this year and the dates they take place. So that you can settle bar bets the ones that have already passed are not removed from the year’s list:

meteorshower1

Clicking on a shower listing gives you more handy details such as the phase of the Moon during the peak, more dates, hourly rate, and a few more details.

Note that there is a similar app for the iPhone that is actually a bit less crude looking than the android app:

Meteorshowerappiphone

The only things is that the Android app is free while the iPhone costs $0.99

Verdict: Good to have!

Next: Telescopes Demystified

teledemyst

This is available for the Android only.

This isn’t really an app, its more of a book about astronomy. A very limited book..and really probably not a very good book. We can start with the fact that the app is called telescopes demystified and then has Telescopes Mystery on the pic and ‘cover’.

The book is divided in to chapters and there is not much rhyme or reason to how they are laid out. Radio telescopes are mentioned, some odd reviews of telescope that made me go ‘really?!’. Only some limited info about actually using your telescope and some chapters just seem like outright ads for telescope models and companies. I tried to evaluate this for someone who was brand new to astronomy and all I can say is: you can do better. Hordes of websites from amateur astronomers do a better job, our own telescope buyer’s guide does a better job. You can get a lot more info than this ‘book’ from wikipedia. I just was not impressed overall.

Verdict: Don’t Bother

www.spectrum-scientifics.com

 

 

 

 

 

 

Starring in March only: COMET PanSTARRS

You may have already heard some buzz about Comet ISON, which has a very good chance of being a very bright and visible comet later this year (2013). But there is a decent chance that we have a preview naked-eye comet this month by the name of Comet PanSTARRS

PanSTARRS

PanSTARRS will make its closest approach to Earth (about 93 million miles) tomorrow – but it really will not be visible despite being at its closest state. Only a couple days later will it creep up over the Western horizon after sunset. On or about March 10th will it start to develop its ‘tail’. In the middle of the Month, the Comet should truly be visible. At time the Moon might interfere. PanSTARRS should be visible in the Western skyline for much of the rest of March.

PanSTpositionNASA

The brightness of PanSTARR is estimated to be about as bright as a star in the Big Dipper. So if you can see the Big Dipper in your night sky, PanSTARR should be visible – albeit more streaky as a comet is want to be.

All of this comet discussion comes with a caveat – COMETS ARE VERY HARD TO PREDICT. A wise astronomer once said ” Comets are like cats – they have tails and do exactly as they please”. Many a comet has done something unexpected resulting in disspointing viewing: breaking up, not have the right tail orientation, etc. On the other hand, it could be even brighter than expected (-1 magnitude, not quite as bright as Sirius).

But hey, if you are out on a clear March night, it won’t hurt to glance Westward.

These links might have more information for your viewing enjoyment:

NASA

EarthSky

Universe Today

www.spectrum-scientifics.com

Spectrum Scientifics Telescope Buyer’s Guide Repost

With the holiday’s coming, we’ll have limited time to post on our blog, so to help holiday shoppers we will repost our Telescope Buyer’s Guide.:

 

Spectrum Scientifics Telescope Buyers Guide

There are several telescope buyers guides available on the Internet, some good, some not so good. At Spectrum we are writing from our experience with customers and hope to make this simple and helpful.

Towards that end, the first and in some ways only rule of telescopes is:

Aperture is King!

Aperture is the diameter of the main lens or mirror of the telescope. The bigger it is, the more light the telescope gathers. Do not judge a telescope by its magnification, and stay away from any brand of telescope that sells itself on excess magnification claims (300x!, 600x!, etc.). This is sure sign of poor quality.

More light gathering means better, brighter images, assuming all other things being equal. Decent commercially sold telescopes usually start about 60mm in size (about 2.3”) and go to 20” diameter or more. Roughly speaking, every 2 extra inches of aperture doubles the light gathering capacity of the telescope.

The big problem with getting more aperture is that it increases the size and weight of the telescope. Having a huge, giant telescope with lots of light gathering power has little benefit if it is so heavy you never want to take it out and use it! A minor, but critical caveat to the ‘Aperture is King’ rule is that the small, portable telescope that gets used all the time is more powerful than the giant telescope that never gets moved out of the garage.

What Kind of Telescope?

There are three types of telescope: Reflector, Refractor, and Cassegrain. For beginners purposes, only the first two should be seriously considered. Cassegrain telescope are very nice, but are a bit advanced for first time scope buyers.

Reflector telescopes use parabolic or spherical curved mirrors to gather and concentrate light. The advantage of reflector telescopes is that they are the most economical for larger sizes. The disadvantages are: in inverted image (meaning a reflector telescope cannot be used for looking down the street) and a need for occasional maintenance: the mirror must occasionally be aligned, or collimated to ensure the telescope is working at its best.

 

 

Refractor telescopes use two or more lenses to gather and bend (or refract) light. The advantage for refractors is that, at equal sizes, they provide a more crisp image of the object being view versus a reflector telescope, refractors also can be used for terrestrial viewing (i.e. Looking down the street again), and they do not need to be collimated like reflector telescopes. The disadvantages to refractor telescopes is that as refractor telescopes get larger, they increase in price at a much faster rate than reflectors. At smaller sizes, say 2-3” in diameter, the prices are roughly equal for reflectors and refractors. But by the time you reach a 5” aperture, the price of the refractor will be at least double that of the reflector.

Due to the difficulty of grinding larger lenses, the weight of those lenses, and an optical effect called chromatic aberration (where the light is broken up as it travels through the refractors lens in a manner similar to prisms) refractors generally are not made larger than 5-6” in diameter.

 

 

What Kind of Mount?

Any telescope is going to need a mount! There are three different mount designs to consider: altazimuth, equatorial, and dobsonian. Whatever mount you decide on, it should be strong enough to hold the optical tube without wobbling. Nothing is more annoying than trying to view an object in the sky, only to have it bounce around and be unwatchable because of a poor mount.

Altazimuth Mounts:Altazimuth mounts are simple mounts designed to help aim the telescope in simple up/down (altitude) and left/right (azimuth). Altazimuth mounts are simple and intuitive, and work well for beginners. They are also useful if you wish to use your telescope for terrestrial viewing. The problem with altazimuth mounts is this: objects in the sky do not move in convenient up/down, left/right motion. They move through the sky in an arc (or at least it seems that way to us!). This means that trying to track celestial objects using an altazimuth mount can be like drawing a curve with an etch-a-sketch! For most beginner viewing, this is not an issue, and one can always reacquire an object that moves out of the field of view. But it does mean that if you find a nice object with your telescope, and leave to go let your friends know, it will likely move out of the eyepiece view by the time you come back!

 

 

Equatorial Mounts: Sometimes called German equatorial mounts, are distinguished by their counterweights that are needed to keep the telescope properly balanced. Equatorial mounts require more setup than altazimuth mounts as they must be adjusted to your latitude and aimed North. They are also not as intuitive to aim as altazimuth mounts as they do not follow left/right up/down motions but instead move along declination and right ascension. This follows the path of stars, planets, and deep space objects, but takes some getting used to. The advantages of equatorial mounts are that they can track objects with a turn of a knob, or they can even be motorized. The other advantage is that with some study, the equatorial mount’s setting circles can be used to actually find objects in the night sky! Equatorial mounts are also required for any type of astrophotography, but for beginners this should not be a great concern.

 

 

Dobsonian Mounts: Some consider the Dobsonian to be just variant of the altazimuth mount, and they are not completely wrong. Dobsonians have the same advantages and disadvantages of altazimuth mounts: intuitive movement, no tracking, etc. But the difference is that a Dobsonian mount uses a lazy-susan style platform to move in azimuth and usually some form of hubs to move in altitude. The result is that a Dobsonian mount can handle much, much heavier optical tubes than most altazimuth tripod mounts are capable of handling. Thanks to several improvements in design, Dobsonian mounts have become more and more popular as they are one of the most economical telescope designs on the market today.

 

 

Other Considerations:

The optical tube and mount are major concerns, but they are not the only things one should consider when buying a telescope:

Eyepieces: Eyepieces are often overlooked when buying a telescope, but they should be considered seriously by the beginner as they are 50% of the overall optical system. Almost all telescopes include 2 eyepieces, but by no means are all eyepieces created equal. Cheap telescopes usually include old, cheap eyepiece designs such as Ramsden or Huygenian designs that actually can make the image worse. The telescope you buy should come with eyepieces that, at a minimum, are Kellner or preferably Plossl design. These eyepiece designs are considered the standard for decent eyepieces.

Finder Scope: Every telescope needs a finder scope, a small telescope that sits on top of your main optical tube and aids in aiming the telescope. Most lower end telescopes these days use a reflex finder which projects a red dot onto an optical window to show where the telescope is pointing. These reflex finders are actually easier to use than a cheap finder scope would be. However, for larger telescopes a 6×30 (which stands for: 6 magnification, 30mm aperture) finder scope is much more appropriate. Larger telescopes may also have even larger finder scopes. Avoid telescopes with old 5x finder scopes, or at least be willing to try and attach some sort of reflex finder in its place.

Optional Accessories: Not everything you need for observing the night sky will come with your telescope (and if it does, beware, some companies gussy up cheap scopes with cheap accessories!). There are some things that should be in any astronomer’s ‘kit’. Such as:

  • A Planisphere

Make certain this is one you can read easily at night with your red flashlight!

  • A Red Light Flashlight :

A red flashlight prevents you from losing your night vision the way a regular (white) flashlight would.

  • A Barlow Lens

A Barlow lens is a lens you slip your eyepieces into that then doubles or triples their magnification. Having a barlow is like doubling the number of eyepieces you have. Make sure you have a barlow before you go buying additional eyepieces.

  • A decent Astronomy book

Don’t just buy a book with pretty pictures. Make certain it is a useful book that gives helpful instructions and advice on how to use your telescope, find& observe night-sky objects and other hints. Make certain to read it fully before you go observing, then refer to it during your observation session.

  • Time and good weather

Make certain that you have time for your new hobby. It takes some commitment for even casual viewing. Also, make certain that before you go observing that the weather is decent for viewing. There’s no point in going observing on a night where haze clouds everything in view!

  • Warm clothing

OK, you should really have this stuff already. But it is important to know. Even in warm summer months the temperature can get surprisingly cool at night. Be certain that you are ready for the weather, wherever you are and whenever you observe.

Other accessories you should consider, but are not as crucial as the above items are:

  • FiltersThere are a lot of filters available, and they all help with viewing certain objects. Moon filters cut down on the bright moon (which can actually be painful to view through a large telescope!). Color filters help bring out features of the planets. Sky Pollution filters reduce (but do not eliminate) the effects of light pollution. Read up on their effects and decide if any of these filters are right for your needs.
  • A Carrying Case (for accessories)Eyepieces, barlows, filters, books, & planispheres! All these little parts can be hard to carry and just shoving them into a bag isn’t a very good idea. Consider buying an accessory case to put your eyepieces, etc in for easy transportation. The time to consider getting a carrying case is when moving the accessories is starting to get in the way of your night sky enjoyment.
  • Binoculars!
  • If you haven’t already gotten a full sized pair, you should. Binoculars make for easy viewing, help find night sky objects. And are great for quick viewing. These need not be specifically astronomy binoculars, just a decent pair of full-sized binoculars will work fine. 

Things Not To Worry About

There is plenty to consider when buying your first telescope, but some things should not be worried about. These include:

Astrophotography:

Astrophotography, even in the age of digital cameras, is pretty advanced stuff that requires a lot of time and equipment. Trying to jump into it, or making your telescope buying decisions based on it, is like learning to swim by jumping into a the deep end of the pool. First make certain that you enjoy astronomy, and can commit the time for basic viewing before you even consider taking up astrophotography. Remember that if you need a different mount than what you initially buy as your first telescope that you can usually sell the old telescope at a reasonable price.

Ultra-High End GPS Super GoTo Computer Guidance Systems:

These systems, while great, can actually be problematic. They are expensive, aren’t the ‘idiot-proof’ systems some folks make them out to be, they limit you from learning about the night sky, and many designs actually require that you aim with the computer. This means if the computer’s motors run out of battery power, you can’t even aim the telescope yourself! Basic guidance systems, such as the Orion Intelliscope line are useful for finding objects in the night sky without taking the experience away from you! Consider these instead of completely controlled systems.

Color!

If one were to look through a book of astronomy picture you would think that every view of the night sky through a telescope is awash in bright, pretty colors. Sadly, this is not the case. Most of these photos are taken with long exposure photography and show colors that, while there, are not apparent to the human eye. Be realistic about what you see, and make certain that the telescope you buy doesn’t have tons of unrealistic photos on its box (which were usually taken by the Hubble Space Telescope or the Viking and Voyager probes!).

Above all else BE READY TO ASK QUESTIONS!  Ask your local salesman, ask for advice online. Don’t be shy! Amateur astronomers may be opinionated but they are more than happy to share their experiences and expertise with you!

www.spectrum-scientifics.com

Science Jigsaw Puzzles, Part 1

We’ve toyed with this notion for a while, and even carried one or two here or there, but until recently we were not very happy with the offerings of science oriented puzzles in the past. That has changed. Poster-company Eurographics decided that they could take some of their many posters and make some good jigsaw puzzles out of them! We have decided to carry a few of them to see how they do. Most of these puzzles are 1,000 pieces ( a couple are 750 pieces) and gorgeously detailed. We have chosen a wide variety of science topics that you can enjoy assembling.

First up up are the astronomy puzzles. The NASA Solar System planet images is very pretty:

And we would not be doing much good if we didn’t have a Night Sky Map Puzzle

And of course we have an impressive Map of the Moon Puzzle

Finally, in the astronomy category, we have this 750 piece puzzle of the Solar System that lays out vertically 12″ x 36″ when assembled:

In part 2 we will cover the puzzles in other science categories:
www.spectrum-scientifics.com

Astronomy Hints #16 Reflector vs. Refractor

This astronomy hints post is going to double cover much of what we covered in our Telescope buyer’s guide but we hope to go into a bit more detail for those considering their first telescope – and that is the raging battle between reflectors (telescopes that use mirrors) and refractors (telescopes that use lenses).

Now we are just concentrating on the telescope’s optical tubes. We won’t talk too much about mounts right now. First let’s take a look at the two designs:

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Now odds are, if you are looking at these two designs and don’t know a thing about telescopes beyond what TV & movies may show your first instinct will probably be to think of the refractor (the one on the left) as being what you think of as a telescope: a tube pointing at what you want to look at while on the opposite end of the tube is the place you look into. Its very simple, and very intuitive. It even invokes the old brass collapsing telescopes every pirate move seems to be require to show by law.

Conversely, the reflector (on the right) can be a bit odd-looking. First of all, the front end is open and empty! You have to look all down the tube to see any sort of optics 013thumb(i.e the primary mirror).  Then you notice that there is no place to look through at the end of the tube. The eyepiece just kind of sticks out of the side, and the finderscope (a little telescope used to help find things in the night sky) isn’t in the same place as the refractor. What is going on here?

Well, what is going on is that while the result is the same (light gathering and magnification), and some of the fundamental optics are doing the same thing, the fact is they are both doing it very differently.
First up the refractor employs a large lens, located at the front of the tube, to refract (hence the name) or bend the light. This bent light is designed to come to form an image very close to where the eyepiece is located (you can get an idea of how this works by making an image of an object on a wall with a magnifying lens – just remember the telescope is designed to have the image form much further away!). The eyepiece then focuses on this image. In a way this is like having a magnifying glass focus on a magnified image – sort of.

Diagram of a Refracting Telescope

Conversely, the reflecting telescope doesn’t bend the light, it reflects it, or bounces it if you prefer. This is similar to what the mirror on your car or in the bathroom does, except that the mirror in a telescope is curved. So it also forms an image not very far from the telescope’s eyepiece:

Reflector Telescope Diagram.

So now that you know how each is different, the question becomes:

WHICH IS BETTER

The fact is: There is no simple answer for this. Let’s just go over some basics.

Let’s start with the advantages

ADVANTAGES

Refractors:

  • Tend to have sharper images
  • Have more traditional designs
  • Do not require much maintenance or collimation

Reflectors:

  • Are less expensive to build at larger sizes

Seems like Refractors are the winner, yes? No, not really.  You see that first advantage of reflectors is a killer. It is simply much easier to make a larger mirror than a large lens for a telescope. With a mirror, you need to polish only one side and coat it. With a reflector, you need to polish both sides at least two lenses (most refracting telescopes use air-spaced achromats (multiple lenses) and will probably need coat them with an anti-reflection coating as well.  That’s four lens sides, each one with a different curve.

The major selling point of refractors at small sizes is their traditional designs & lack of need for collimation. A small refractor will cost about as much as a small reflector and will give a beginning astronomer fewer things to worry about. The other advantage, the sharper images,  tends to only come with higher-quality refractors or even what are known as apochromatic (3 or more lenses, or two very well designed ones) objective lenses. These can get very expensive, but at small sizes (i.e. easy to transport) the refractors can easily win out with image quality. Many astronomers, not wanting to haul around heavy reflectors, may opt for these advanced refractors.

Let’s look at the other side of the coin:

DISADVANTAGES

Refractors

  • “Chromatic Abberation” – where the lens breaks up the light like a prism
  • More expensive than reflectors at mid and large sizes.

Reflectors

  • Requires occasional maintenance/collimation for ideal viewing
  • “Secondary Shadow” from secondary mirror will cause some loss in the light gathering

Chromatic Abberation can be annoying when viewing bright objects (the Moon, Jupiter, Venus, etc) as it results in what is known as a “violet fringe” around the object. This can be filtered out, and it doesn’t show up much on dim objects (light galaxies, nebulea, etc.) . But it can be frustrating to some novice viewers.  More critical to refractors is the expense of making medium and large-sized models. We already covered why in the advantages section.

Reflectors on the other hand have the problem with collimation. Most large reflectors are probably going to need collimation if they’ve been moved around a lot. They will still work if they aren’t precisely collimated, but the images will appear streaky. Collimation can be a bit tricky to master and so can frustrate novice astronomers.

The secondary issue is bit of a misnomer. What it essentially says is that any reflector telescope is not going to gather as much light as its full surface area as a portion of it will always be in the shadow of the secondary mirror. This is mostly just a nuisance as if one needs more light gathering power one simply makes a larger primary mirror., but then weight does become an issue.
So to answer the question of ‘which is better’, there really isn’t much of a straight answer – at small sizes (for beginners)  there is little reason to not get a refractor. But once the sizes get larger the reflector very quickly becomes much more economical. These rules are in no way ‘hard and fast’ as there are many exceptions to them. But as an overall guide they can give you an idea of what design to look at.

www.spectrum-scientifics.com

5 Planets Visible

This isn’t rare, but it isn’t really common either. This month (or at least this week) astronomical viewers can have a chance to see 5 planets in a single evening.

After sunset, Mercury will be visible just above the horizon in the West sky – and we do mean just. Trees and houses may block your view of Mercury. However Venus and Jupiter will be more visible right above them also right after sunset, nice and bright, along with Mars, which while still not in occultation is pretty bright, rising in the East  just after sunset.

Later in the evening, Saturn will rise in the Eastern sky – this is the only planet you will need to wait for  as it is not immediately visible after sundown.

Although Mercury may be blocked by buildings, all of these planets can be seen with the naked eye, even in light-polluted areas.

For your best viewing be sure to get an area with a clear horizon so that all the planets can be seen.

Happy viewing!

www.spectrum-scientifics.com

Painless Learning Educational Placemats!

We’ve got a new line of products here at Spectrum – and its a product for the dinner table! We’ve added several products from the Painless Learning placemats. These are 17-1/2″ x 12″ heavily laminated placemats with detailed color fronts that give information on a wide variety of science & math subjects, the backs of the placemats are in black-and-white and can either be colored with dry erase markers or have a short quiz to see what kids using the placemats have learned!The placemats are economical at just $3.99 so you can buy a bunch and rotate them over a couple of weeks!

We have a lot of these placemats, so here is just a small sampling:

USA Map Placemat

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Be sure to check out the World Map Placemat as well.

There’s the Solar System Placemat:

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There is also the Stars & Constellations Placemat as well

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For more on some basic learning there is a Multiplication Tables Placemat.

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Be sure to also check out the Sign Language Placemat, Learning About Money Placemat, and Time to Tell Time Placemat.

For more science orientations there is the Periodic Table of Elements Placemat:

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Science placemats also include the Weather Placemat, Human Body Placemat as well as this Rocks & Minerals Placemat:

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We also have a Dinosaur Placemat (natch).

In all there are 15 different placemats to choose from! be sure to pick up some for your next meal!

www.spectrum-scientifics.com

The Orrery and other Solar System Simulators

An Orrery is a mechanical simulation model of the motion of the planets in our solar system. An Orrery demonstrates how the planets move in orbit around the sun in relative motion to the other planets. So in  a properly designed Orrery if the Earth model goes around the sun 30 times then Saturn will have circle the Sun just once. More advanced Orreries will even have the various planets rotate with an appropriate period, and very advanced models may have moons which in turn orbit the planets with the proper period.

Orreries were the ultimate in mechanical devices in Astronomy. Universities would spend fortunes to build them in varying sizes and features. They could be as small as a desktop model, to as large as a closet. Today there are some Orreries in museums that take up entire rooms! Many older models are still around, albeit not operational and they show how our knowledge of the Solar System has changed – older models may not have all or even most of Jupiter’s moons, Mar’s two moons are often depicted as perfect spheres, and so on. The most amusing are the older models built before the discovery of Pluto – they were naturally built without that dwarf planet, and this absence was noted for many decades – until Pluto was demoted from planetary status and the old Orreries became accurate once more!

Orreries are almost never perfectly to scale – they are meant to show orbital periods, not accurate distances from the sun. The planets are often oversized as well, but that is necessary for the visual presentation.

These days, few large Orreries are built outside of museum entrance halls. Computer simulations on screens cover most of the mathematical needs, but very often students of Astronomy may need a decent physical demonstration of plnaetary rotation. Fortunately, there are some Orreries still being manufactured! Not just Orreries, but several kinds of solar system simulations!

First up we have a classic powered Orrery. This is a simple model showing just the Major planets – no moons, no dwarf planets, but it does use a classic gear driven system to work out the proper planetary periods! The model moves quietly  and includes a Teacher’s guide with 10 lesson plans! This model is perfect for classroom or home schooling for ages 8-14 (grades 3-9).

For a more economical model, we also have the Solar System Simulator. This model does not operate on gears, instead the planets are adjusted using the dates printed on the base. The planets are moved to show their position around the sun.

No Astronomy class plan would be complete without demonstrations to show how the Earth and Moon move around the Sun. For that we have the Earth-Moon Orbiter Simulator

This simulator is manually gear driven and can be used to show the various aspects of the Moon revolving around the Earth and the Earth in turn revolving around the sun!  Daylight, night, seasons and phases of the moon are all demonstrated with this model. But perhaps you want to show a bit more? For that we also have an Illuminated Earth-Moon Orbiter Simulator

With this simulator you cover the same topics as the non-illuminated model, but with a much more effective visual aid as with an actual illuminating ‘sun’ give the effect of what light from the sun actualy does!

These models are excellent for the classroom or for pooled equipment among home-schoolers.

www.spectrum-scientifics.com

Comet Lovejoy lives!

We just have some time to say a few words: One of the more interesting astronomical events of this year was Comet LoveJoy and its near suicide run to the sun. Turns out it survived and is now visible with the naked eye – in Australia – before dawn. Check out the video!

Comet Lovejoy (2011 W3) rising over Western Australia from Colin Legg on Vimeo.