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Author Topic: Re: Are other planets/moons useful?  (Read 1011 times)

Offline chiralSPO

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Re: Are other planets/moons useful?
« on: 13/07/2015 15:52:51 »

Apart from Earth and the Moon, do any other planets have any 'use'?


I assume this question is asking if other planets are useful for humans (hypothetical beings on Europa might not think that our moon is very useful...)

If that is the case, I would say that Jupiter is definitely "useful." It played a very important role in determinging the structure of the solar system, and continues to shield the inner planets from comets and the like.

I would also argue that many of the planets and moons in our solar system have been very useful to us because we have learned so much from observing them. Countless stars and planets have been incredibly useful for navigation and development of accurate calendars. Early observations of the motions of Venus in the sky aided in the development of some mathematics and astronomy. Discover of the moons around Jupiter allowed us to realize that the geocentric view of the universe held at that time was ill-founded. Careful observation of Jupiter's moons was used for very accurate time-keeping before clocks were reliable enough. Laws of gravitation were developed by analyzing the paths of planets and comets, and Einstein's theory of gravitational distortion of spacetime was confirmed by careful measurements of Mercury's orbit. The first few planets discovered outside our own solar system (exoplanets) have revolutionized (and will probably continue to do so over the next few decades) our understanding of our own solar system, and the workings of the universe on a larger scale.

Need I continue?  :)
« Last Edit: 13/07/2015 20:31:13 by chiralSPO »


 

Offline PmbPhy

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Re: Re: Are other planets/moons
« Reply #1 on: 13/07/2015 17:58:27 »
Quote from: thedoc
Apart from Earth and the Moon, do any other planets have any 'use'?
Yes. Jupiter is often used to help send spacecraft to other planets using gravity assist, aka the slingshot effect. Nasa has a page on this at: http://saturn.jpl.nasa.gov/mission/missiongravityassistprimer/   and    http://www2.jpl.nasa.gov/basics/grav/primer.php

There's more online at:
http://www.scientificamerican.com/article/how-does-the-slingshot-ef/
http://www.ams.org/samplings/feature-column/fcarc-slingshot
https://en.wikipedia.org/wiki/Gravity_assist
http://www.esa.int/Our_Activities/Space_Science/Exploring_space/Let_gravity_assist_you
http://www.qrg.northwestern.edu/projects/vss/docs/navigation/3-slingshot.html
http://www.mathpages.com/home/kmath114/kmath114.htm

You're fortunate because I was reading the book Gravity from the Ground Up by Bernhard F. Schutz and just finished reading the portion on gravitational assist. Otherwise I might not have readily recalled this and others might not have thought of it either. While its a common problem in physics its not something we all readily recall off hand.

The Earth's moon was important in the beginning and evolution of life.
« Last Edit: 13/07/2015 18:00:12 by PmbPhy »
 

Offline evan_au

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Re: Re: Are other planets/moons useful?
« Reply #2 on: 14/07/2015 11:34:49 »
As stepping stones for space exploration?
  • At 380,000km, the distance to the Moon is about 10x circumference of the Earth.
  • With a closest approach of around 130 million km, Mars is about 340x further again.
  • At an average distance of 6 billion km, Pluto is about 46x further again.
It's a very big step from Pluto to Proxima Centauri, at 1013 km, so maybe we need some intermediate stepping stones there, too...
 

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Re: Re: Are other planets/moons useful?
« Reply #2 on: 14/07/2015 11:34:49 »

 

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