Basic Astronomy

Will Mars look like as big as Moon on 27th Aug? Not really


26th August 2013: The well known Mars hoax has come again. Each year, before 27th August, this hoax reappears.

This year also it is circulated again in many social networking sites that Mars will look as big as Moon on 27th August. It will be a really a great view if this is true but unfortunately the story is a hoax.

Double moon Facebook hoax image
Hoax image of double moons in Facebook.

As both Earth and Mars are rotating around Sun, the distance between two planets vary dramatically over time. The maximum distance is about 250 million miles and it occurs when Earth and Mars are on opposite sides of the Sun. Similarly, the minimum distance between these two planets is about 33 million miles and it occurs when Earth and Mars on the same side of the Sun, with Earth at its farthest distance from the Sun and Mars at its closest distance. So, the apparent size of Mars also varies a lot with the variation of distance between Mars and Earth. When Mars is far from Earth and small in size, it can be seen only by telescope but when the red planet is relatively nearby it looks as a small disk in sky.

Mars comes within about 50 million miles of Earth once every 18 months or so. Because the orbit of Mars is more elliptical than Earth's orbit, it does occasionally get within 35 million miles.

The last closest approach of Mars occurred on August 27, 2003 at 12:30 a.m.

The story started when some astronomers posted a Power Point presentation about two months before last closest approach of Mars discussing the event on the Internet. This presentation was not well organized or detailed but its content was completely scientifically accurate.

In one slide of the presentation, a comparison was made to indicate how large Mars would appear when viewed through a typical amateur telescope. It said "at a modest 75 power magnification..., Mars will look as large as the full Moon to the naked eye." What was meant by this statement was that The Mars with telescope would appear as large as the full Moon appears when the full Moon is viewed without a telescope.

However, in the final presentation, the statement "at a modest 75 power magnification..." appeared at the bottom of one slide, and the statement "Mars will look as large as the full Moon to the naked eye" appeared on the next slide.

The original presentation was viewed by very few people, one of whom republished it as a simple text email, but left in a line break between those two parts of the key sentence.

Elsewhere, in the presentation and in the email, the closest approach date was mentioned as August 27th, and the time at which Mars reaches the highest point in the sky was 12:30 a.m.

It was also mentioned that the next time Mars will be this close to Earth is in the year 2287, and, in big bold letters, "NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN".

That email was then sent out and copied to millions of people, with most of the other parts of the text removed.

As a result, every July and August since 2003, we see a recurrence of these emails or other Internet message types, carrying the same message.

In fact, for most of the viewers in world, Mars isn't even visible in night time sky this year."





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