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I have fond memories of our first summer at anchor in Turkey. Many an evening would be spent sitting in the cockpit at night, enveloped by the surround sound of cicadas and gently lapping water. Liz and I would position the old Acer laptop upon the table and boot up Redshift, an astronomy package that allowed us to view the sky at night. With our lon and lat programmed into the computer’s system and the laptop pointing towards the same aspect as the boat’s bow we were able to quickly learn the stars above. Having this kind of information at one’s fingertips is a great way of understanding the constellations of the sky and a useful way of passing night watches. In this brief post I look at a free astronomy app called Stellarium, which is ideal for anyone with just a small interest in the stars.

My copy of Redshift 4 was old, bought off Amazon second hand many years ago. Computers and the technology used to run them have moved on since then and now that we use a 10 inch netbook as our primary computer I can no longer run Redshift 4 on a small screen resolution. Redshift 7 is the latest incarnation but it cost a few dollars to purchase. For the record the most popular paid-for astronomy apps are Redshift 7 and Starry Night, but I was interested in finding a free astronomy package with similar features to the ones I was used to.

Redshift 7 and Starry Night are quite sophisticated but as a boat-owner with just a passing interest in astronomy there are many features I don’t need in an astronomy application. As long as I live on the water I’m never going to own a telescope, so I don’t need my app to talk to and move said telescope. There is much of deep-space that I don’t need to know about either and I don’t need an animated history of the universe, even if it is educational. All I am interested in, and I suspect all most amateur star-gazers are interested in, is identifying what the stars are above our heads that we can see with our own eyes. Of course there are billions of stars but the average human eye can only see around 3,500 at any one time, so there is a lot of data I don’t require. That said the software can be used to help identify stars, planets and moons that are visible using a pair of binoculars, and since every boat owner has at least one pair of bins on board having a fairly sophisticated level of information is useful. Liz and I are able to see Jupiter’ moons using our bins, for example, and an astronomy application can help visualise what to look for.

There is a comprehensive list of free astronomy packages here, for both Mac and PC.

The two that frequently came out in search results were Cartes Du Ciel and Stellarium. Cartes Du Ciel is Open Source and actually boasts a number of features that Stellarium doesn’t have. However the interface looks more at home on a ZX Spectrum, such is the dated format of the application. This is true of many of these freebies. Stellarium, on the other hand, is not only intuitive and modern, but has a comfortable, warm feel to it as well.

Upon opening Stellarium one is presented with a 360 degree panoramic view of a field, with the points of the compass on the horizon. This has an instant appeal but I was delighted to find that I could change this image to a number of different vistas from snowy forests to the moon. I could even put in a panorama of the ocean, making me feel more at home!

 

 

The two main menus are simple roll-overs on the bottom and left of the screen and are pretty self-explanatory. In fact the key to Stellarium is that it is extremely intuitive. I downloaded and ran Cartes Du Ciel as a comparison and found myself stumbling on every mouse click, despite it being a more powerful package.

One useful benchmark test I ran was to identify Jupiter and view its moons. In Stellarium this is easy. Just pull up the search window, type in ‘Jupiter’ and the animated screen will move so that Jupiter is centred on the screen. The real gem, however, is being able to roll the mouse wheel to zoom in on your subject, and in this instance Europa, Ganymede and Callisto are all there, labeled and moving with Jupiter as the application animates the movement of the sky in real-time. I guess Io was hiding behind the planet at the time. Redshift 4 was able to do this but not with such grace and ease. No doubt Redshift 7 boasts this feature but remember Redshift 7 costs over $60 to purchase and Stellarium is free.

 

Jupiter and its moons

 

Most Important Features
Having used Redshift I did have a number of expectations with Stellarium and I am pleased to say that it has them, albeit more stripped down. Here are the important features for me:

 

  • current location – the ability to input lon and lat coordinates, time of day, location etc.
  • animation – simple animation of the movement of the sky, allowing the user to be aware of what is going to happen in the sky throughout the night. It moves in real-time with the system’s clock.
  • labels – obvious but very important, with labels of constellations, stars, clusters, planets and moons
  • filters – a simple slide-bar allows the user to increase and decrease the amount of labels visible
  • search – I didn’t realise I needed this until I saw it, but now I use it frequently

Other Features
Here’s a quick summary of some of the other features Stellarium has. You can find a full list of features, taken from the webite, at the end of the article:

  • projection – pre-set filters to view the horizon and sky in a number of ways, including Mercator, the projection used in many nautical charts
  • night vision – similar, if not better, than Maxsea, the ability to turn the entire screen a hue of red in order to preserve the viewer’s night vision
  • move telescope – despite me not needing this feature Stellarium does offer this should you own a telescope and mount.
  • ability to add one’s own panoramic landscape, made up of .png files


Summary

Stellarium has instant appeal. It is one of the only completely free astronomy applications that has a modern feel to it; many of the more established titles like Cartes Du Ciel feel dated. To a heavy computer user like myself, and to any person under 20, Stellarium just ‘feels’ better.

It is not the most sophisticated package out there and it lacks a lot of features that others boast, but this is almost a boon. By simplifying the interface it makes it a whole lot more accessible and appealing to an amateur astronamer such as myself, and it’s going to appeal to children and the not-so-savvy computer user.

As a boat owner I’d like to see additional features including the moon and its phases, something that the paid-for packages feature as standard. Also the right-hand mouse button doesn’t do anything, which I think is missing a trick as a way of accessing extra information.

A more serious amateur astronomer would probably be better served with a more sophisticated package but for me I find Stellarium perfect for my requirements, which is simple star-gazing and identification of the brightest stars seen with the naked eye.

 

Full List of Features For Version 0.10.5, taken from the Stellarium website

sky

  • default catalogue of over 600,000 stars
  • extra catalogues with more than 210 million stars
  • asterisms and illustrations of the constellations
  • constellations for twelve different cultures
  • images of nebulae (full Messier catalogue)
  • realistic Milky Way
  • very realistic atmosphere, sunrise and sunset
  • the planets and their satellites

interface

  • a powerful zoom
  • time control
  • multilingual interface
  • fisheye projection for planetarium domes
  • spheric mirror projection for your own low-cost dome
  • all new graphical interface and extensive keyboard control
  • telescope control

visualisation

  • equatorial and azimuthal grids
  • star twinkling
  • shooting stars
  • eclipse simulation
  • skinnable landscapes, now with spheric panorama projection

customisability

  • plugin system adding artifical satellites, ocular simulation, telescrope configuration and more
  • add your own deep sky objects, landscapes, constellation images, scripts…