What if the sun was any closer to the Earth ?

Question

A friend of mine told me that if the sun was the slightest bit closer to the Earth, it'd be too hot for anybody to live on, and if the sun was the slightest bit farther away from the Earth, it'd be too cold for anybody to live on . IS THIS TRUE ? I know the sun is closer to the Earth during the summer, so I'm suspicious . Does what my friend told me have any basis in fact, or was he mistaken ?

Answer 1

The sun is not necessarily closer to the earth in summer. In general, aphelion occurs sometime in January (the date is not constant), so it is summer in the Southern hemisphere. However, the seasonal variations in temperature are not caused by distance but by the tilt of the planet relative to its orbit, so the southern hemisphere faces the sun during the Dec - Mar months, and the northern hemisphere faces the sun during the Jun - Aug months.

As for the earth's distance -- it IS true that the earth occupies the "habitable zone": that distance from the mother star (in our case the sun) where the planet receives a suitable amount of radiation to sustain life. However, this range is not so narrow as one might presume. In our solar system, Mars is also in the habitable zone. However, it is too small and lacks a magnetic field, and so is unable to maintain a sufficient atmosphere to sustain any meaningful life. (The jury is still out as to whether there might be trace microbial life on Mars.)

Answer 2

I'd like to know your source for this. What is more likely is that this is a misinterpretation of a correct statement. Someone else on these boards asked why you get colder when you go higher, since you are getting closer to the Sun but, as many people pointed out, a few thousand feet is nothing compared to the millions of miles between Earth and Sun. As for the people who answered here saying the seasons are caused by distance from the Sun, I could really despair at that. I was taught in school the correct reason for the seasons. Why weren't these guys? The tilt of the Earth's axis causes seasons, not distance. When it is winter in the northern hemisphere the Earth is actually closer to the Sun. The reason it is winter is because the tilt of Earth's axis makes the Sun's rays strike the Earth at an oblique angle, hence they are spread out over a greater area on the surface, whereas in summer they strike from more directly above. (To understand what I mean here, shine a torch onto a wall from about two feet away. When you hold the torch parallel to the ground you illuminate a small bright circle on the wall. If you tilt the torch the circle extends to a dimmer ellipse, covering a larger area but with the same amount of light.) That is possibly where this misunderstanding arose. It IS colder here on Earth in the northern hemisphere when Earth is closer to the Sun. However, that has to do with the tilt of the Earth, not the distance.

Answer 3

Not true. Also, not true the Earth is closer to the sun in summer. It is the tilt of the axis which determines the season because of the direction that sunlight falls on the surface of Earth, not the change in distance as we orbit. Our orbit is an ellipse. Aphelion is the name for the furthest point away. Perihelion is the name for the closest point of approach which happens 6 months after aphelion, of course. These points do not coincide with the seasons of summer and winter as you might suspect, but in reality actually happen a couple of weeks offset. The difference between perihelion and aphelion is about 3 million miles. The number of 93 million miles away from the sun is just an average. Note that perihelion happens near the middle of winter for the Northern hemisphere,

Here are a list of dates and times I picked up from wikipedia:

Year Perihelion Aphelion
2007 Jan 3 20Z July 7 00Z
2008 Jan 3 00Z July 4 08Z
2009 Jan 4 15Z July 4 02Z
2010 Jan 3 00Z July 6 11Z
2011 Jan 3 19Z July 4 15Z
2012 Jan 5 00Z July 5 03Z
2013 Jan 2 05Z July 5 15Z
2014 Jan 4 12Z July 4 00Z
2015 Jan 4 07Z July 6 19Z
2016 Jan 2 23Z July 4 16Z

Answer 4

YES and NO...
We are always fluctuation as to how close we are to the Sun. The earth travels on an elliptical path, which by definition gets closer and further from its points at all times.

And the margin of error on the distance that we exist from the sun is pretty liberal. If the Earth were 1 mile closer to the Sun or further away it would be irrelivant, but from your question is that "the slightest big closer"? The average distance from the Earth to the Sun is 92,000,000 miles....where 1 Million miles is just over 1% of the distance. That distance would probably make changes to Earth as we know it, either closer or further...

Answer 5

"Slightest bit" is a relative term. If you had a picture drawn to scale of the solar system (with the earth smaller than a grain of sand and the sun about the size of a small beach ball and about a km away--or something to scale of that) it would seem like a little bit compared to the rest of the solar system.

Too close to the sun and the greenhouse effect (which keeps the earth a comfy temperature now) would be too much, the water would evaporate, and water which is a greenhouse gas, would contribute to the greenhouse effect. We would be definitely Venus' "sister" planet then!

Answer 6

Well... it's true to a degree, but.... Right now, the Earth has an elliptical orbit. At our farthest, we're about 94.5 million miles away, and at closest about 91.9 million miles. That's a difference of about 3 percent (and about 3 million miles!) every 6 months. (Strangely - when we're *closest* to the sun, the northern hemisphere is experiencing winter!) So... there's defintitely some 'play' in the distance, but where the point is that things become too hot or too cold - well, it's more than 3 million miles.

Answer 7

Your friend is mistaken, but only slightly. The earth has many reasons it has kept it's temperature for millions of years.
1) The water zone. (Distance from a star at which water remains in a liquid or gas form for some time)
2) Earth's Electromagnetic field: It shields us from the harmful Solar winds that would rip our atmosphere apart. This is my strongest reasoning that earth could be much closer to the sun and still survive. Possibly even up to 25% closer.
3) Atmosphere: Green house gasses and other inert gasses in the atmosphere regulate the absorbed sunlight and UV radiation received 24x7. With the right amount of C2O and other greenhouse gasses our earth could still sustain life if we were further out in the solar system.

It all comes down to the earths ability to absorb and regulate solar energy in all its forms. So many factors contribute to it that any one of them can disrupt or amplify sustainable temperatures on earth over a vast distance in our own solar system!

Answer 8

The water zone is a little wider than earths orbital eccentricity. A few million Km closer or farther would make a major difference though.

Answer 9

Around every star there's what's commonly known as the "habitable zone." Any planet within that zone is considered to have conditions under which the development of life is possible.

Earth obviously lies within the habitable zone of our sun and remains within that zone regardless of our orbit around the sun being elliptical (..BTW :: Earth is closest to the sun in *winter*, not summer..)

To answer your question then -- if Earth's mean distance from the sun was 74,365,704.3 instead of its current 93,000,000 miles then we'd be outside the habitable zone and existing life here would be seriously endangered.

Answer 10

A little bit in astronomical amounts is millions of miles. He is correct, but it would be much greater than the eliptic that we already have.