I saw something about Mars shortly being at its closest to the Earth in some thousands of years, which in itself may be true. Like the nonsense from a few years back, it went on to say that Mars would appear to be like a second Moon in the sky.
All I can say is that shows a singular lack of understanding of math, and geometry in particular, not to mention astronomy. Lets look at the numbers, and pardon me for rounding. It should not distort the results appreciably.
The Moon has a diameter of 2159 miles, while Mars has a diameter of 4212 miles. Just looking at that, Mars has twice the diameter of the Moon. But the distance is an even more important factor. The Moon is roughly 238,000 miles from Earth, while Mars at its closest is 33,900,000 miles from Earth.
What we see is how wide it APPEARS to be, which is a factor of both diameter and distance. That can be expressed in degrees of an angle. The Moon will have an apparent size of 0.525 degrees, while Mars will have an apparent size of 0.0071 degrees. That means the apparent diameter of the Moon will be about 74 times the diameter of Mars.
When you then look at the whole size, in terms of area, size the area of a circle is pi times the radius squared. The radius of the Moon would be 74 times the radius of Mars, so a full Moon would be some 17,000 times bigger in apparent area than Mars at its closest approach.
I trust that if my calculations are askew, that my mathematician friends will correct me. None of this will stop the fools who want to believe that Mars will appear as big as the Moon in the sky.
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