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June 17th, 2015 at 11:15:51 AM permalink

Ayecarumba

Member since: Oct 24, 2012
Threads: 89
Posts: 1744

Quote: Dalex64
This is not correct. In a compressed sun, the mass has not changed, and the distance between the planets and the center of mass of the sun has not changed.

The density of the sun has changed. The gravitational attraction would remain the same.

Same thing when the sun goes red giant. Density goes down, mass remains the same, planets not swallowed by the new sun will remain in the same orbit.

The sun is losing a little mass all the time due to radiation (sunshine!) but we aren't talking about that yet.

Hmm, I did some checking, and you are both correct that the effects of gravity will remain constant over the solar system's current orbits if the sun were compressed. However, the orbits of the planets will change when the sun goes red giant, as it will lose mass during the transition to that stage (e.g., the Earth will move out to where Mars is now).

June 17th, 2015 at 1:00:49 PM permalink

Dalex64

Member since: Mar 8, 2014
Threads: 3
Posts: 3687

Quote: Nareed
That's actually very small. Photons have no mass.

I'm not sure if you are forgetting about the mass/energy equivalence or not.

This page talks about how much mass the sun loses every day due to mass being turned into energy and being radiated away: http://solar-center.stanford.edu/FAQ/Qshrink.html

Quote:
In units of tons, every second, the Sun's fusion processes are converting about 700 million tons of hydrogen into helium "ashes". In doing so, 0.7 percent of the hydrogen matter (5 million tons) disappears as pure energy. (My reference for this paragraph is "The Sun" chapter in _The New Solar System_ editor: Beatty and Chaikin, Sky Publishing Press.)

now, IMO "disappears as pure energy" is poorly worded, especially considering that it is believed to take 1,000,000 years for a photon to escape the sun.

"Everyone is entitled to his own opinion, but not to his own facts." Daniel Patrick Moynihan

June 17th, 2015 at 1:04:25 PM permalink

Dalex64

Member since: Mar 8, 2014
Threads: 3
Posts: 3687

Quote: Ayecarumba
Hmm, I did some checking, and you are both correct that the effects of gravity will remain constant over the solar system's current orbits if the sun were compressed. However, the orbits of the planets will change when the sun goes red giant, as it will lose mass during the transition to that stage (e.g., the Earth will move out to where Mars is now).

Interesting thing related to that, from http://www.universetoday.com/12648/will-earth-survive-when-the-sun-becomes-a-red-giant/

Quote:
One interesting side benefit for the Solar System. Even though the Earth, at a mere 1.5 astronomical units, will no longer be within the Sun’s habitable zone, much of the Solar System will be. The new habitable zone will stretch from 49.4 AU to 71.4 AU, well into the Kuiper Belt. The formerly icy worlds will melt, and liquid water will be present beyond the orbit of Pluto. Perhaps Eris will be the new homeworld.

"Everyone is entitled to his own opinion, but not to his own facts." Daniel Patrick Moynihan

June 17th, 2015 at 2:01:04 PM permalink

Nareed

Member since: Oct 24, 2012
Threads: 346
Posts: 12545

Quote: Dalex64
I'm not sure if you are forgetting about the mass/energy equivalence or not.

No, but a mass particle would drain the Sun of mass sooner.

Quote:
now, IMO "disappears as pure energy" is poorly worded, especially considering that it is believed to take 1,000,000 years for a photon to escape the sun.

Some of the energy produced by the fusion reaction stays within the Sun. Photons take long to leave because they are refracted, absorbed, reemitted, etc. some of the heat remains, too, which heats up the hydrogen before it gets fused.

Donald Trump is a one-term LOSER

June 21st, 2019 at 4:19:15 PM permalink
petroglyph Member since: Aug 3, 2014 Threads: 25 Posts: 6227	https://www.ibtimes.co.in/big-bang-theory-wrong-universe-itself-exists-inside-gigantic-higher-dimensional-black-hole-799674?fbclid=IwAR0-gSoMnS68z3suEregoWJKjUxCq10xIqx_hm1MJ8rdV9bKmr7yEkY3O80 Alternative hypothesis to the Big Bang. The last official act of any government is to loot the treasury. GW

June 22nd, 2019 at 12:27:02 PM permalink
rxwine Member since: Oct 24, 2012 Threads: 189 Posts: 18762	Quote: petroglyph https://www.ibtimes.co.in/big-bang-theory-wrong-universe-itself-exists-inside-gigantic-higher-dimensional-black-hole-799674?fbclid=IwAR0-gSoMnS68z3suEregoWJKjUxCq10xIqx_hm1MJ8rdV9bKmr7yEkY3O80 Alternative hypothesis to the Big Bang. Maybe someone will create a nice animation of this. You believe in an invisible god, and dismiss people who say they are trans? Really?

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