# Exploring Our Solar System with Wolfram|Alpha

August 3, 2009
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Wolfram|Alpha contains a wealth of astronomy data on many areas of our universe, such as objects within our solar system and in the deep sky, constellations, and computational astronomy, making it a handy resource for astronomers, students, and hobbyists. Some of the most intriguing space activity takes place right here at home, inside of our own solar system. Wolfram|Alpha makes computations and explores properties and locations for objects and events in our solar system, such as the sun, planets, planetary moons, minor planets, comets, eclipses, meteor showers, sunrise and sunset, and solstices and equinoxes. You can query any one of these objects or phenomena, and learn information such as their position in the sky relative to your location, size, or distance; their next occurrence; and much more.

Wolfram|Alpha automatically assumes your geographic location based on your IP address, which is handy when querying for the time and location of an upcoming sky event. For instance, a quick “lunar eclipse” query in Wolfram|Alpha tells us that, for our location in Champaign, Illinois, the next one will occur on August 5, 2009 at 7:38pm U.S. Central Daylight Time and will be penumbral, which means the moon will enter the Earth’s penumbra (the outer part of its shadow), resulting in an apparent darkening of the moon. A penumbral eclipse is often hard to see because the penumbra isn’t very dark.

Wolfram|Alpha can also provide interesting facts about distances, temperatures, and dimensions of objects in our solar system that are specific to the time of day and your location. What is unique about querying Wolfram|Alpha for an object’s distance is that the distance is returned in real time, based on where the Earth is in its orbit. A textbook can only provide an average distance. For instance, at the time this post was written, Wolfram|Alpha reported that the sun was approximately 1.015 astronomical units (94.35 million miles) from Earth—enter “Sun” to see its current distance.

Wolfram|Alpha also reports plenty of less time-sensitive data about the sun, such as its apparent and absolute magnitude, spectral class, surface temperature, and mass.

In the coming weeks we will explore more interesting and useful astronomy data for stargazing, exploring deep-sky objects, and computational astronomy. Has anything interesting been happening in your night’s sky? You can connect with enthusiasts from around the world having this conversation at the Wolfram|Alpha Community site.

A feature hard to find somewhere else is to calculate the distance between planets at any date:

http://www18.wolframalpha.com/input/?i=distance+from+venus+to+mars+23+oct+2008

I want to give some other implementation suggestions:

Distance between two moons (it doesn’t work currently):

http://www18.wolframalpha.com/input/?i=distance+from+io+to+europa

Distance between planets (other than Earth) and space probes:

http://www18.wolframalpha.com/input/?i=distance+from+Mars+to+Pioneer+11

Plot of distances:

http://www18.wolframalpha.com/input/?i=plot+distance+from+Mars+to+Earth+from+1+jan+2009+to+31+dec+2009

Regards!

Posted by igo August 3, 2009 at 2:01 pm

igo,

We have passed your great suggestions along to our astronomy team! Thank you for the feedback!

Posted by The PR Team August 6, 2009 at 8:35 am

Someone wrote:
“A feature hard to find somewhere else is to calculate the distance between planets at any date”

Unfortunately, the ephemerides used in Wolfram|Alpha (and Mathematica??) are rather crude. For example, the position of the planet Jupiter can be wrong by a substantial fraction of a degree (e.g. on January 1, 1800, the position is wrong by over 28 minutes of arc). This would frequently correspond to errors of physical distances between planets greater than a million miles. It’s hard to see why the astronomical data in Alpha is so inaccurate. I’ve been doing this sort of thing for thirty years, and my best guess is that the algorithms are the fairly primitive ones published fifteen to twenty years ago when computing resources were memory-starved (probably one of the works of Jean Meeus?). The positions of the planets for several hundred years around the current date should never be wrong by more than a tenth of a second of arc.

-FER

Posted by Frank Reed September 19, 2009 at 8:27 pm

it wanted to be able to make calculations with distributions. For example to solve the differential equation f’(x)=D(x), where D is the Dirac’s delta.

Posted by T August 4, 2009 at 8:49 pm

Thanks for good tips and advices. (As I remember, “distance from Earth to Mars” was one of my first questions to Alpha ;-)

Posted by Artaborian August 5, 2009 at 8:34 am

I’m very sorry, but where is my _last_ post about “distance from Earth to Mars” query (this query works strange)? (Aug 5, about a minute after my first comment). I saw, it have passed moderation, but disappeared in a few minutes…

Posted by Aritaborian August 6, 2009 at 2:57 pm

Thanks for sharing this much useful information about solar system with Wolfram | Alpha. I am waiting to read your coming week post.

Posted by Solar Products August 10, 2009 at 2:52 am

Very nice.
I could tell you similiar story.
Will you look at metheor shower this night?
I read it will be great show.

Posted by Watch Metheor Shower August 12, 2009 at 11:13 am

So, about my lost (2009-08-05) comment.

’twas about “distance from Earth to Mars” query.
In May it worked well. But now it seems, it doesn’t work!
Input: distance from Earth to Mars
Input interp: distance | from world to Mars,Pennsylvania,United States
Result: 5697 miles
Then go “unit conversions” and “direct travel times”.
And then goes the map. Hmm, I didn’t know (but I suspected it ;-) that “Earth” is GeoPosition[0,0].
But the main queston is: why the default interpretation for “Mars” is not-well-known American city, but not planet Mars?
The second question is: why, with such interpretation, I still see sidelink to “Mars” article in Wikipedia (yes, planet Mars)?

And of course, despite all of this, I still can learn about the distance from Earth to Mars. Query “distance from Earth to planet Mars” works very well :D

Sorry for boring, but I hope I can help you in our great deal: making all the world knowledge computable :-)

Posted by Aritaborian August 12, 2009 at 2:49 pm

And one more.
I’ve just explored a fun bug in Alpha engine.
Making a typo in “distance from Earth to Mars” query and typing “distance rom Earth to Mars”, I’ve got some really _strange_ result. Namely:
Input: distance rom Earth to Mars
Note: Assuming multiplication | Use a list instead
Input interp: distance | from Automatic to Rome,Lazio,Italy Mars | distance from Earth
Result: (1.707 AU (astronomical units)) distance | from Automatic to Rome,Lazio,Italy
Oh, _what_ does it mean?

Posted by Aritaborian August 12, 2009 at 2:58 pm

Aritaborian,

Our team is looking into the linguistics issues that are occurring in these examples. We appreciate your feedback!

Posted by The PR Team August 12, 2009 at 4:46 pm