Astronomy 101 for the home: view the planets in stunning detail on your PC

Astronomy 101 for the home: view the planets in stunning detail on your PC

Discover how Google Sky, Microsoft's WorldWide Telescope, and dedicated software such as Starry Night or Stellarium allows you to explore the stars and view the planets in stunning detail without even touching a telescope

2009 - the International Year of Astronomy - finds the amateur pastime in rude health. Despite the seemingly unstoppable rise in light pollution and the technical challenges of studying the stars, many thousands of Australians still maintain a watch on the night sky. It helps that astronomy appears to be experiencing a renaissance.

Between the interest in the universe generated by images from the Hubble Space Telescope or Mars landers, and the hype over internet services such as Google Sky, space is occupying the media in a way that it hasn't since the heyday of the space shuttle.

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This shot of the Andromeda galaxy required many exposures to make. Photo by Nick King,

PC technology lies at the heart of the biggest revolution in amateur astronomy. Google Sky, Microsoft's WorldWide Telescope, and dedicated software such as Starry Night or Stellarium allow us to explore the stars and view the planets in stunning detail without even touching a telescope. Yet there's still something special about watching the stars first-hand, knowing that the light you're seeing has travelled hundreds of light years to get here, and that you're seeing it without the mediation of a CCD or screen. PC technology can't make that experience accessible to everyone, but it can make it more approachable, with the use of digital cameras and CCDs for advanced astro-imaging.

This is a great time to get involved. Maybe you just want to sit back and explore the skies solely on your screen. Perhaps, you want to create your own computer-controlled observatory or simply learn a little more about what you can see through affordable binoculars. Either way, we're going to help you make it happen.

Google versus the universe
Google Sky (the Sky layer in Google Earth) is probably the most accessible and widely used method of studying the might of the night sky from a PC. Simply by dragging your way around the screen and zooming in and out of the image, you can look at stunning deep-space imagery from the Hubble Space Telescope, the Chandra X-Ray observatory and others, clicking on the various icons to view relevant information on what you're seeing.

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One of the fun extras provided by Starry Night is a spaceship simulator. Explore space at the speed of light. Click to Enlarge.

Keith Cooper, editor of Astronomy Now magazine calls it an excellent tool for "introducing more people to astronomy and the night sky", explaining that "people who use Google Earth now log on to Google Sky and see pictures of stars, planets and galaxies, often for the first time, sparking what we hope is a lifelong interest in the universe".

Crucially, Google Earth's easy content creation tools, based on the KML mark-up language behind Google Maps, give astronomers and enthusiasts a great way to share information and observations, from real-time alerts on new discoveries to galleries of user-created astro-imagery.

However, in terms of getting to grips with the fundamentals of astronomy, Google Earth isn't the best option. It's hard to relate the way Google Earth presents content with the way we might see the stars. While you enter your postcode in Google Earth then switch to the Sky view to see the stars above your house, there's no way to view the horizon, the very thing that puts the stars in context in the sky.

Starry Night, The Sky, and Stellarium
This is the sort of facility that astronomers require from more feature-rich, dedicated programs such as Starry Night, The Sky or the much-admired, open-source "planetarium", Stellarium. These packages give you more exciting ways to explore the universe, complete with 3D-rendered planets, stars and nebulae, all moving in realistic simulation of their own orbits and the Earth's rotation.

What's more, they allow you to set a home location (for example, your back garden), set a time and get a clear picture of what you might expect to see, complete with simulated horizon and - if you desire - light pollution. From here, you can jump off to explore the stars with binoculars or telescope, although there's easily enough educational and entertainment content in Starry Night or The Sky to keep you busy on a cold, cloudy night. In Starry Night, for example, you can trace the progress of various space missions, or take a spacecraft out for your own trip through the solar system.

Microsoft's Worldwide Telescope
Between Google Earth and the specialist apps sits a third option: Worldwide Telescope (WWT) from Microsoft's Research division. WWT offers the 3D planets, horizon simulation and accurate motion of the dedicated apps, but combines it with the educational and content-creation features of Google Sky. Plus, it's free.

WWT is the superior product in many ways, marrying excellent planetary and deep-space imagery with a slicker interface and superb content-creation features shaped around the concept of tours. Not only can you follow tours created by various astronomers, institutions and publications, you can also make your own using text, voice-over and images you import or capture. It's also easy to flip between observing objects in the visible spectrum and the radio, infrared, x-ray, gamma and microwave spectrums used by professional astronomers. At present, WWT hasn't captured the imagination of a wider community in the way Google Earth has, and some features are distressingly US-biased, but as a tool to explore the planets or make the cross into "practical" astronomy, it's arguably a better bet.

Live imagery from telescopes
There's one other web-based service that might appeal to armchair astronomers, and that's SLOOH. SLOOH gives you access to live imagery from large, well-situated telescopes in the Canary Islands, Chile and here in Australia; you can follow preset missions to specific planets or objects, or "reserve" control of the telescope and target it yourself for a five-minute period. At US$50 for a year of access or US$15 for 100 minutes, SLOOH isn't cheap, but it's cheaper than buying your own telescope and - if you live in a metropolitan area with its consequent heavy light pollution - you'll see an awful lot more.

Computer-controlled telescopes
Virtual astronomy can be an end in itself. As Robin Scagell, vice-president of the Society for Popular Astronomy, puts it, "there's quite a big gulf between looking at Google Sky or whatever and actually taking it up practically", and many users "are as likely to be content with that and just say ‘wow'". However, if using Worldwide Telescope or SLOOH gives you the astronomy bug, PC technology can help you take your interest much, much further.

Plan an evening's viewing
At the simplest level, you can use a program such as Stellarium, Starry Night or WWT to plan an evening's viewing, working out a list of objects to observe then getting your bearings as to how to see them, using the classic "starhopping" technique where you find obvious landmarks, such as the stars in Orion's belt, and use them to find nearby objects (for example, the Orion nebula). You don't have to splash out on a telescope to begin with. Astronomy Now's Keith Cooper recommends "a pair of 10 x 50 binoculars to get started; they're inexpensive and you'll be surprised how much you can see through them".

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One of the fun extras provided by Starry Night is a spaceship simulator. Explore space at the speed of light. Click to Enlarge.

Web-based resources such as Weather Underground can help plan observations in advance, and if you have a laptop you can take your star charts out with you. Just lower the brightness or use the special "red screen" mode in your chosen astronomy program so that your eyes stay adjusted to the darkness.

Buying a telescope - the GoTo mount
If you're willing to invest more, you can buy a telescope with what's called a GoTo mount. These start at $800 for a Celestron NexStar SLT or Meade ETX, and are designed to align themselves automatically using location information you provide and available features of the night sky. After this, you can control them with a simple handset and get them to point at anything in their library of stars, planets and deep sky objects at the press of a button. What's more, with a cable - sometimes optional, sometimes supplied - you can hook them up to a PC or laptop and use a program such as Starry Night, The Sky, Stellarium or WWT to control the telescope and find objects in the same way. If you already have a laptop, you can set up a computerised observatory for under $1000.

Admittedly, the effectiveness of these mounts shouldn't be exaggerated. According to the SPA's Robin Scagell, many people buy GoTo telescopes in the belief that "they'll just look through the telescope and everything will be there".

"You still have to put in a fair amount of interest and expertise," he warned. "Even though most GoTo telescopes will give you a tour of the objects in the sky, they still require you to get out there and get your telescope going." Nor should beginners expect to see Hubble-style clouds of space dust and glowing nebulae. "I'm pretty sure that people might have greater expectations of what they can see through a telescope than what you can see, particularly with the smaller ones," Scagell notes.

Shooting stars
The real breakthrough in amateur astronomy, however, has been the pairing of digital imaging with telescopes. Ten years ago, getting decent images of the stars was difficult for two reasons. First, capturing the small quantities of light emitted on film meant long exposures of 90 minutes or more. Second, unless you kept your subject firmly in frame for the whole exposure, manually adjusting the direction of the telescope using a guide star, your final image would be blurred.

The Deep Sky Stacker
Today, a typical digital image of the same subject can be captured in several shorter, digital exposures of five to 20 minutes in length, with the different exposures montaged together using specialist - some open-source - processing packages such as Deep Sky Stacker, PixInsight, Nebulosity or Maxim DL. "Now, with the affordability of CCDs, webcams and digital cameras that can take long exposures, motorised mounts to smoothly track the object you're imaging, and the software to process images, some of the pictures that amateurs are taking are truly capable of rivalling some of the professional stuff," argues Astronomy Now's Keith Cooper. "That has been the biggest leap in the last decade."

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Worldwide Telescope helps make sense of the cosmos through a series of interactive multimedia tours. Click to Enlarge

Note the mention of webcams. Certain cheap webcams, carefully modified, make surprisingly good astro-imaging devices, and have been adopted by the DIY-loving astronomer. They're light enough to be fitted to smaller telescopes, and there's no need to worry about tracking. You simply allow your object to traverse the aperture of your telescope, capturing images at 60 frames per second, then stack and process those images as you would those from a high-end digital SLR. "Webcams have transformed planetary photography and lunar imaging," said Robin Scagell. "I can go [...] and buy a webcam for less than five bucks, and take a better picture with a small telescope than I could have done with a larger telescope ten years ago on film."

Some of the modified webcams have evolved into more expensive but higher performance CCD imaging devices, such as those from Atik or Artemis, although the website sells more wallet-friendly pre-modified webcams.

Why a CCD beats your naked eye
Astro-photography isn't merely a question of impressive images. For some, astro-imaging has been astronomy's saviour when light pollution is making the practice unviable in most urban areas; the image produced by a CCD will beat anything you can see with your eyes through the telescope. "If it hadn't been for technology, I think astronomy would have declined quite considerably - and the reason is because of the increase in light pollution," Scagell said. "Recently I saw a picture from a friend, and if I'd seen it 25 years ago I'd have said that it had to be taken from the Arizona desert - but he lives in a city!"

The red spot on Jupiter
Amateur astronomy shouldn't be allowed to decline: it remains one of the few areas of scientific interest where the non-professional can still make an impact. In 2006, an amateur astronomer, Christopher Go, found a second red spot on Jupiter. Even though the discovery of comets has increasingly moved to automated surveys, amateurs still make the odd find, and it's novices who still do the bulk of observations on things such as variable stars, or alert the professionals to new supernovae.

The Galaxy Zoo project

As Keith Cooper points out: "You don't even have to look through a telescope any more to make an astronomical discovery." He points to the Galaxy Zoo project, which uses volunteers to classify galaxies imaged in deep-sky surveys. Professionals haven't the time to do the work, and computer analysis isn't as reliable at picking out the shapes and patterns of galaxies as humans. "So you log on to the Galaxy Zoo website, look at different pictures of galaxies, many of which have never been seen by humans before - you're the first! - and you classify them. If you find something unusual, then you're named as the discoverer." Who'd have thought it: your own galaxy, and you don't even need to get up from your chair.

If you liked this article, you might also like our guide to How to see deep space imagery with Worldwide Telescope on your PC


This feature appeared in the June, 2009 issue of PC & Tech Authority Magazine
Copyright © Alphr, Dennis Publishing

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