Mars as big as the Moon

Can Mars really appear as big as the Moon?
  • It is impossible for Mars to appear as big as the Moon from earth.
  • This myth has been spread by a hoax email.
  • Though Mars is much bigger than the Moon, it is too far away to ever appear as big as the moon. Its orbit path will never come close enough to earth.
  • Mars’ size does change noticeably throughout a year though a telescope, as the orbits around the sun pass closer or further from each other, but never to the size of our Moon.
  • Mars only ever looks like a star to the naked eye - depending on how close it is, it can reach a magnituide of –2.9 with the moon a much brighter magnituide of -12.7.
  • Mars is smaller than Earth but larger tan the Moon if they were physically side by side
  • When the Moon and Mars are separated by their distance from Earth, Mars shrinks to a tiny size. Their distance apart can range from 55 million (pictured) to 400 million kms apart
  • The ‘apparent size’ of the Moon and Mars, or how big they look from earth, literally demonstrates the size of Mars and the Moon combined with their distance away from earth.
  • The scale used to measure the apparent size is degrees (o), minutes (‘) and seconds (“), of which has nothing to do with time.
  • The sky is divided up into 360 degrees, right around the horizon, and also vertically, right around  over your head and beneath your feet.
  • There are 60 minutes in a degree and 60 seconds in a minute – therefore 3600 seconds in one degree of the sky.
  • The apparent size of Mars changes because the orbits of Mars and Earth are not exactly centred. Some times when these planets are at the same point of their orbit, and at their ‘closest’, it depends on where in their uneven orbit they are coming close to how big Mars looks from Earth.
  • At its absolute closest to earth, Mars appears about 25"(sec) in size. At its most distant position, Mars  only appears 3.5”(sec) in size.
  • The Moon’s apparent size ranges from around 29’(min)80”(sec) to 33’(min)40”(sec)
  • If we convert the moons size into just seconds to compare it with Mars - the biggest Mars appears is only ever up to around 25” (sec)  however  the smallest the Moon appears is  around 1820” seconds.

  • You can see, poor Mars, thought bigger in actually physical size is too far away to ever be even close to appear as big as the moon.
  • If Mars was close enough to appear as big a the Moon there would be some catastrophic changes to some gravitational pulls.