I recently saw a post claiming Mars was going to appear as large is the full moon to the naked eye. That would be REALLY COOL… assuming it was real. Whereas my inner “I wish that was true” jumped with glee, my BS alarms went off and my hopes and dreams subsequently came crashing down.
This is an interesting hoax that started in early August of 2003. At the time, Mars was due to pass “very” close to Earth, the closest pass of the two planets since 57,617 BCE. It will be the closest the planets will be to one another until at least 2287. For some distance perspective, this closet point of this pass was about 55,763,108 km (or 34,649,589 miles).
For some perspective, here are some numbers for you:
- The average Earth-Moon distance is 384,400 km (238,900 mi).
- The Moon orbits 145 times closer to the Earth on average than Mars will be when it passes Earth at this 56-million km mark.
- Mars has a diameter of 6787 km and the Moon has a diameter of 3476 km meaning Mars is about twice as large as the Moon.
What would it take for Mars to appear the same size of the Moon in our sky? Since Mars is twice the Moon’s size, it would have to be within two-times the average Earth-Moon distance. In other words, Mars would have to pass within about 768,800 km (477,800 mi) of Earth (or, about 72 times closer than its 2003 pass).
According to NASA, if Mars were to pass close enough to Earth to make it appear the same size as the Moon in the sky, Mars would be close enough to Earth to adversely affect our orbit and wreak havoc on our tides (and, it would probably screw the Moon over too). In other words, it’s not pretty.
The hoax consistently places this phenomenal event to occur on August 27, so it’s affectionately been deemed “Mars Hoax Day.” This hoax has resurfaced every year since 2005 and shows no sign of slowing down.
Alas, Mars is doomed to appear no larger than a star point to the earthbound unaided eye. If you were standing on Mars, however, I’m fairly certain it would appear larger than a star point and the full moon.