Were There Two Moons in the Sky on August 27?

Mars Close Approach Happens Every 26 Months on Different Dates

Mars and the moon both clearly visible in the night sky.

jmbaud74/Flickr/CC BY 2.0

A recurring online rumor that has been circulating since 2003 claims that August 27 of a given year will bring "the closest encounter between Mars and Earth in recorded history," during which, supposedly, Mars will appear as large as the full moon and it will look like there are two moons in the night sky.

It's nonsense. Mars is never close enough to Earth to appear as large as the full moon. It's true that an event similar to this occurred on August 27, 2003, as Mars was closer to the Earth than it had been for almost 60,000 years. NASA says it won't be that close again until the year 2287. However, there are recurring close approaches about every 26 months, so the late August date won't be valid for most close approaches in your lifetime.

During the Mars close approach on July 31, 2018, it appears larger than it did on the May 30, 2016, close approach. But with your naked eye, Mars won't look much larger than normal. It will still be a bright, non-twinkling star, not a moon. With a telescope or strong binoculars, you will be able to see it is disc-shaped.

Example of the Rumor as Circulated in 2007

FW: TWO MOONS
MARK YOUR CALENDARS FOR THIS
** Two moon on 27 August ***
27th Aug the Whole World is waiting for.............
Planet Mars will be the brightest in the night sky starting August.
It will look as large as the full moon to the naked eye. This will happen On Aug. 27 when Mars comes within 34.65M miles of earth. Be sure to watch the sky on Aug. 27 12:30 am. It will look like the Earth has 2 moons. The next time Mars may come this close is in 2287.
Share this with your friends as NO ONE ALIVE TODAY Will ever see it again.

2015 Example

12:30 Aug 27th you will see two moons in the sky, but only one will be the moon. The other will be Mars. It won't happen again until 2287. No one alive today has ever witnessed this happening.

Analysis of the Two Moons Rumor

You can't keep a good rumor down. These claims were semi-accurate when they first began circulating in the summer of 2003. They were outdated by the time they went around again in 2005, however, and just plain false when they appeared in 2008 under the header "Two Moons on August 27." The rumor circulated yet again in 2009, 2010, 2011, 2015, 2016, and so on.

How many times can a "once in a lifetime" event occur? Well, just once. On August 27, 2003, the oscillating orbits of Mars and Earth did, in fact, bring the two planets closer together than at any other time during the past 50,000 years. And although Mars never actually appeared "as large as the full moon to the naked eye" — not even close (and not even possible) — it was, for a rare few days in 2003, among the brightest objects in the night sky.

Mars Close Approaches

In the July 31, 2018 event, Mars is still 35.8 million miles away from Earth. In 2003, it was less than 35 million miles from Earth. Check NASA for coverage of upcoming close approaches. These can be a good excuse to buy a telescope and plan a vacation to a place with clear night skies.

NASA plans its Mars missions to launch approximately every two years, so they will arrive at Mars during one of these close approaches. By doing so, they save millions of miles of travel distance.

Why Close Approaches Happen

The orbits of the Earth, Mars, and other planets are not circular. Orbits are oblong, and each planet orbits the Sun in a different period of time. For Earth, that is 365 days (one year). Mars takes about 687 Earth days to circle the Sun. Earth passes by Mars about once a year. Some years, that happens when Mars is farther away from the center of the solar system (the Sun) and during other years, it is when Mars is closer to the Sun (and therefore to the Earth).

However, at no time is Mars so large that you would think it is another moon.

Sources

Giovanni. "The Two Moons Hoax E-Mail." Urban Myths, July 21, 2010.

"Mars Close Approach to Earth." NASA.

"The Big Mars Hoax." Astronomical Society of South Australia, Inc.

"Twin moon post a hoax." Northglen News, August 21, 2014.

Vookoti, Siddhartha. "Mars Coming Close to Earth on 27th August, Will Look Like Second Moon — Facts." Hoax or Fact, 2019.