If electromagnetic radiation can tranmit in vaccum (no medium effect), what factor it can be weaken?

Question

Extended question of the following:
http://answers.yahoo.com/question/;_ylt=AiPPCagXfv73N_pu5G3Gzy0jzKIX?qid=20060718193121AADm3o7

if the sun send out electromagnetic radiation and it can tranmit in vaccum, then there should be not friction nor any effect. Therefore, all planets in solar system should receive same amount of electromagnetic radiation and form the heat by the planets. Each planets should have close temperature, how come the temperature have huge difference than others?

Therefore, I may say each planets should receive different electromagnetic radiation (I am not sure, correct me if i am wrong). But what factor form each planets to receive different electromagnetic radiation?

enginerd, you hit the answer i want. I think i am clever now. Thank you very much

Answer 1

you are right about the fact that the light is not being weakened much as it travels through space (it is weakened some because space is not a perfect vacuum), that's why we can see light from galaxies million's of light years away

however, the reason that solar radiation falling on outer planets is weaker, is because the light has spread

if you had a sphere surrounding the sun at the distance of the earth, it would catch all the radiation, and a sphere out at pluto would also catch it all, and the total energy that hit either sphere would be similar

however, the pluto sphere is way way bigger

the amount of solar radiation hitting any square mile of the pluto sphere would be tiny compared to what would hit a square mile of the earth-distance sphere

since the light is spreading in all directions, the area intensity (as in how much light would hit a square mile sheet at that distance) is dropping off by the cube of the distance, and thats a lot

Answer 2

Gosh, If you only think about what you asked, you should have already figured this out. For example, you have dust and all sorts of rocks, meteor, gases, even black holes. All this things affects the light transmitted by the sun. The other thing is the further out the plants or stars are, the colder they get. I do believe that even though light particle travels at the velocity of 186,000 mi/sec., it will eventually at some point looses it's momentum and therefore loosing it's energy as it travels across a vacumn space. having said this, it is then possible for each planet to have different temperatures. However, it is also save to say that, some planet do produce their own heat within the core due to surface pressure. I mean it's clear that even our earth core is quite unstable, and it is producing heat all the time.

Answer 3

Light intensity from a point source drops off as the square of the distance from the source. Sufficiently far away, stars can be considered point sources. The reason is the same light energy is spread over a larger area, and that area increases as the square of the distance (area of a sphere = 4*pi*r^2). However, perfectly collimated light, as might be formed by a lens and a point source, or a laser, would theoretically not lose any intensity with distance, since the area of the light beam would not change. In practice, however, it is impossible to achieve perfect collimation. Laser beams come close, and that is why laser beams can be used to communicate over long distances (such as to the moon and back, as has been done). Even perfectly collimated beams would lose intensity if there were any light absorbing material in its path.

Your question brings to mind "Olber's Paradox". If stellar light sources are uniformly distributed throughout the universe, the sky should be brighter than the sun both day and night! Why? The number of stars with in a "shell" of radius r from the earth increases as r^2; the light intensity from each star decreases as r^2. This means that even though distant stars are dimmer, there are more of them so the total radiation stays the same. From that, we would expect that the sky should be as bright as if it were filled with suns. This wasn't really resolved until Hubble discovered the expansion of the universe, in which more distant stars are moving away from us, and the farther away, the faster they move. Thus light from distant stars loses energy and do not contribute to the lighting of the sky.

Answer 4

Listen up buddy u cannot predict the temperature that way...as far as the radiation is concerned u r right on target but see the amount of heat transfered depends upon the solid angle subtended by the face of the planet on sun and that's lesser as u move away from sun so the heat is less......and thus the temperature varies....The Titanic(Moon of jupiter) is said to have Ice volcanoes that emerge out of the ground to a certain height and then bend to a 90 degree angle amazing isn't it...The universe is full of miracles......Man will learn it slowly but still most of it will remain unexplored...

Answer 5

since the energy from the sun is more or less ent off in all directions, you can think of a sphere expanding outward with the sun in its center.

the surface of this sphere can be thought of as 'all the energy emitted by the sun in a particular short period of time' (let's say one second)

As this sphere expands, all the energy from that one second is distributed over the entire surface, so as the surface area increases, the 'energy per square inch' decreases.

If you double the radius of a sphere, you increase its surface area by 4 times (the change in radius, squared)

So, by the time the radius of the sphere matches Jupiter, the surface area is about 25 times larger than it was at earth, so only 1/25th the amount of energy is available.

Since Jupiter is bigger than earth, a bigger piece of the sphere hits it.

In fact.. Jupiter's diameter it 142K Km, and earth's is 12K.. so the delat in diameter is about 12.. so that's about 144 times more surface area than the earth.. divide that by 25 and you get about . So even though Jupiter is way farther away, it is so big that I guess in theory it has access to about 6x the total solar energy that the Earth gets.

Planets don't particularly efficiently absorb energy 'at an angle' so the actual difference is probably different than 6.

Mars, on the other hand is both farther away AND smaller, so it gets much less solar energy than the earth. Plus it has a weeny little atmosphere which can't efficiently trap the energy it does get.

Answer 6

hmm... as far as my thinking goes, the size of planets also determines how much radiation is incident on them. Also, if a planet is further away, the radiation is spread far and wide and hence less of it is incident on the planet itself. Thats why the difference.
And besides that, a third factor could be in the difference in the ability of the planets and their atmospheres to retain that heat. Some release that heat back into space, hence chillin themselves ;-)

Answer 7

Electromagnetic radiation is weakened by
divergence: it spreads. (Read about inverse square law.)
In the intergalactic, interstellar and interplanetary space is few gas, plasma and dust. The radiation can loose its energy by absorption, Doppler effect and Compton effect both giving redshift, and by polarization.
Th