The search for exoplanets—planets orbiting other stars—is one of the hottest topics in astronomy, as the total number of confirmed discoveries approaches 900, with several thousand more likely planets awaiting confirmation. We’ve reviewed one very good exoplanet-related app, the Editors’ Choice Journey to the Exoplanets—an informative and visually stunning iPad app. The app reviewed here, simply named Exoplanet (4 stars, free), is also worthy of an Editors’ Choice. This free app works with the iPhone as well as iPad, but I reviewed it with the latter (an iPad 2) as it provides a better view of the app’s amazing graphics.
In essence, Exoplanet is a catalogue or database, based on the Open Exoplanet Catalogue managed by the app’s creator, Hanno Rein. It contains detailed information on every confirmed exoplanet discovery. But far from being a stodgy and static database, Exoplanet has a striking visual component: it includes 3D animations of each of these (879 and counting) newfound planetary systems. These range from single-planet systems to ones with up to 7 known worlds. Our own solar system is included for comparison; in addition to the 9 planets, the app shows the tracks of four spacecraft (Pioneer 10 and 11, and Voyager 1 and 2) that are leaving the solar system.
Exploring the Exoplanet App
The app’s home page gives you 6 choices: Database; Exoplanet News; Background Information; Milky Way; Correlation Diagrams; and About/Add-ons. The Database consists of a vertical list of all the confirmed exoplanets, and includes the planet’s mass (in Earth masses), orbital period, eccentricity, discovery method, discovery year, date of last update, radius (in Earth radii), distance (in light-years), and the mass of the planet’s star. Planets in the table are identified by star name plus a letter (starting with “b”, as “a” is reserved for the star itself). The more letters, the more planets a star has: for instance Iota Draconis only has one planet listed, Iota Draconis b, while Gliese 876 has four planets (Gliese 876 b, c, d, and e), and HD 10180 has 7 planets, going all the way up to h. At a glance this may seem rather geeky, but read on.
If you click on one of the planet names, let’s say HD 10180 h, you’ll see a brief textual description of the planet and its system. Along with the 7 large worlds in this system, which orbits a sun-like star in the constellation Hydrus, two more worlds are awaiting confirmation. It was discovered by the HARPS spectrograph in Chile; there’s an illustration of the discovery method, the position of the star in the night sky, and a pictorial representation of the planetary system. Below these diagrams is a list with detailed information on the planet and its host star, as well as links to scientific publications about it.
The iPad as Starship
The real fun comes when you click on the second item on the list, Find System in Milky Way. You’ll seem to zoom out from the previous star you’d visited, to show you a panoramic view of our galaxy, and then zoom in on your chosen star. As you approach, the star’s system of planets is revealed in motion as an animation, which you can rotate to view from any angle, as well as pinch or stretch for a close-up or wide-field view.
The planets are depicted in their true orbits (as best we know them) and sizes relative to each other, though they are larger than is actually the case, to make them easily visible. They are all depicted as gray spheres, which is fitting as we know nothing about their surface features, and can only guess at their composition.
Journeying to the different planetary systems and noting their diversity is a mind-expanding experience. When I’ve used the app on the subway, I’ve found that it’s a great conversation starter, as several people have looked in rapt attention over my shoulder and asked me what it was that they were seeing.
From this “starship” view you can e-mail, tweet, post to Facebook, print, copy, or save a screenshot of the animation to your camera roll. You can also access information about the Milky Way view, search for your next planetary target (for example, Alpha Centauri Bb, the planet recently discovered in the star system nearest to Earth, adjust settings such as zoom speed and the orbit speed of planets, the addition and subtraction of constellation lines and the like.
News and Other Features
The Exoplanet News section briefly notes the latest exoplanet discoveries and other relevant items. You can receive these as push notices as well. Exoplanet News gives a basic yet solid overview of exoplanetology, the different methods of detecting these worlds, and the different types of worlds being discovered.
Milky Way gives a 3D view of our galaxy, which lets you zoom in and see the locations of all known exoplanets relative to the Sun, which remains in the center of the field of view as you zoom in and out. Correlation Diagrams lets researchers, and the curious, plot different exoplanet characteristics against each other, drawing from the full database of confirmed planets. For instance, you could correlate the radius of exoplanets versus their orbital periods. You can save the results in PDF form and e-mail them, as well. About/Add-ons gives you 3 choices for in-app purchase: Galaxies and CMB (the cosmic microwave background radiation) ($0.99); Kepler Objects of Interest (the addition of yet to be confirmed Kepler planet candidates to the database); and Remove Ads ($1.99).
The app has been consistently revised and improved; it’s now in version 9.8. The one issue of note that I’ve encountered is that it crashes now and then, and you may have to shut your iPad off and restart it for the app to work again. But that’s a small inconvenience in what otherwise is an informative and visually striking app that reveals pictorially all the new solar systems that astronomers are discovering.
Journey to the Exoplanets, the other Editors’ Choice exoplanet app, is an ebook collaboration between Scientific American and Farrar, Straus and Giroux. It has beautiful artists’ renditions of how these new worlds might look, and informative text that should appeal to younger students and interested laymen.
The Exoplanet app reviewed here, on the other hand, is more of a catalogue or database, providing detailed information about all known discoveries. It provides an overview of the study of exoplanets as well. What really sets it apart, and also makes it an Editors’ Choice, is the wonderful set animations of all the confirmed planetary systems. Although some of the app’s content is admittedly quite geeky and suitable for advanced students or researchers, these animations should appeal to most anyone with the slightest interest in science, and spark the imaginations of a new generation of astronomers.
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Copyright © 2012 Ziff Davis, Inc