My boss at work is forever forwarding emails to the group.He is an internet newbie, so most of the stuff is recycled chain stuff. But I don’t tell him to stop because sometimes the jokes or pictures of scantily clad women brighten up my day. Plus I also get a chance to debunk them to the group by using a couple of the hoax/urban legend sites I keep bookmarked.
Today I got one that shouted at me in various colors and fonts that Mars will be passing the closest ever to Earth this August. Be sure and tell your kids and grandkids because it won’t get this close for another thousand years. Well, I remember that this actually happened 2 years ago, so I replied all asking where did I sign up for the time travel trip and linking to a page describing that this was an event that occurred in 2003.
After I sent that back, I starting reading the whole email and near the bottom was two pictures, one of the Moon and one of Mars about the same size. Underneath were words to the effect, “Starting at the beginning of the month you will be to watch Mars grow in the sky until it is the same size as the Moon to the naked eye, so enjoy the show.”
A little more research and I just had to sent out another email to the group addressing this statement. Mars is roughly twice the diameter of the Moon, 6878km vs. 3476km. For them to appear the same size to the naked eye Mars would have to be roughly twice as far from Earth as the Moon. The Moon is 368,500km from Earth, so doubling that (let’s round up a bit) gives us 800,000km. Lets switch to something we can grasp and convert the 800,000km to 500,000 miles. Mars would have to be 1/2 million miles away to appear the same size in the sky as the moon to the naked eye. Now 1/2 million miles sounds pretty far away, but at Mar’s closest approach to Earth two years ago, it was 35 million miles away. If the red planet finds a way to get that close to us, something is seriously wrong with our solar system. Nobody will be enjoying the show, they will be preparing to die.
Actually this October there will be another close approach. Mars will be a mere 43 million miles away and it will appear in the sky to be the size of a quarter viewed from an 1/8 of a mile away.
My cubical neighbors got to talking about what kind of effect the Martian gravity would have on Earth if it got as close as stated n that email. Back to the web for more research. The mass of Mars is 6.4219e23kg. The mass of the Moon is 7.35e22kg. That is a lot of zeros to try and type into Windows calculator, so seeing as we are just after the ratio, let’s divide 64.219 by 7.35. This gives the answer that the mass of Mars is 8.73 times that of the Moon. For Mars to look the same size in the sky as the moon it has to be twice as far away as the Moon. Because the force of gravity is inversely proportional to the square of the distance between two objects, the force of gravity of the Moon would be ? of what it is if it was twice as far away. So if it Mars that same twice as far away it’s effect would be 2.18 time stronger than that of the moon. I suppose that would make the tides twice as high. And if the Moon and Mars got close to aligning in the sky the tides would be 3 times as high as they are now.
Any Planetary Physicists out there feel free to chime and let me know how far off my calculations are.
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