The Naked Scientists

The Naked Scientists Forum

Author Topic: Why do the outer gas giant planets reflect light?  (Read 1569 times)

Offline thedoc

  • Forum Admin
  • Administrator
  • Sr. Member
  • *****
  • Posts: 511
  • Thanked: 12 times
    • View Profile
leaded1 asked the Naked Scientists:
   
I would like to know if the ancient people like Copernicus, and even before them, had good knowledge about the stars for they were much closer than today, that's if the bigbang theory is correct.

And if scientists think that everything started from our universe. Why does the outer gas planets reflect light at nighttime, also gas fusions or what. They talk about multiple universes, is it possible for them to collide or are they all moving outwards.

What do you think?
« Last Edit: 19/07/2013 18:30:02 by _system »


 

Offline RD

  • Neilep Level Member
  • ******
  • Posts: 8132
  • Thanked: 53 times
    • View Profile
Re: Why do the outer gas giant planets reflect light?
« Reply #1 on: 19/07/2013 19:13:16 »
I would like to know if the ancient people like Copernicus, and even before them, had good knowledge about the stars for they were much closer than today, that's if the bigbang theory is correct.

The positions of some stars have noticeably changed during human history, e.g. ...

Quote
There have been many pole stars throughout the millennia. Around 2000 BC, the star Eta Hydri was the nearest bright star to the Celestial south pole. Around 2800 BC, Achernar was only 8 degrees from the south pole.
http://en.wikipedia.org/wiki/Pole_star#Effects_of_Axial_Precession

But the stars were not noticably closer during human history than today, even using the latest telescopes all but a few are points of light.

... Why does the outer gas planets reflect light at nighttime, also gas fusions or what.

According to NASA Jupiter is self-luminous and also reflects light from the sun ...

Quote from: NASA
the internal energy leftover from the formation makes Jupiter self-luminous, radiating away more energy than it receives from the Sun.
http://www.lpi.usra.edu/decadal/opag/jupiter_2009whitepaper.pdf

although the radiated energy must be tiny compared with the reflected sunlight , (or invisible), as parts of Jupiter can appear black ...

http://www.jodrellbank.manchester.ac.uk/astronomy/nightsky/
« Last Edit: 20/07/2013 09:59:23 by RD »
 

Offline CliffordK

  • Neilep Level Member
  • ******
  • Posts: 6321
  • Thanked: 3 times
  • Site Moderator
    • View Profile
Re: Why do the outer gas giant planets reflect light?
« Reply #2 on: 19/07/2013 20:53:35 »
Keep in mind orders of magnitude

14 Billion years (age of the Universe by current theories.
4.5 Billion years (age of Earth by current theories)
145 to 201 Million years (Jurassic period, also the time of the evolution of the first mammals.
5 to 10 Million years (Evolution of the first Hominid)
200 Thousand years (Evolution of first Homo Sapien)
40 Thousand years (Oldest known cave art)
30 Thousand years (Domestication of Dogs, and early farming).
11 Thousand years (Beginning of the Holocene.  Most of our "History" dates to this period, or just before it).
2 Thousand Years (Roman Empire, Jesus, etc.  Perhaps the beginning of Modern History).
500 Years (Copernicus).

Anyway, if you think of the proportion of the distance stars have moved since the Big Bang and Copernicus, you would get about 500/14,000,000,000. and one gets a tiny fraction of the total distance the stars have moved.

Even pushing it out to the time the first hominid skulls appeared, we have the changes are less than 1/1000 of the current distance.

 

The Naked Scientists Forum

Re: Why do the outer gas giant planets reflect light?
« Reply #2 on: 19/07/2013 20:53:35 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums