Mars Hoax

Howard L. Cohen, Emeritus Assoc. Professor, Dept. of Astronomy, Univ. of Florida, Gainesville, FL 32611
July 29, 2005 (Updated Aug. 26, 2005)

Don't be misled by erroneous info circling the Internet about the 2005 Mars opposition

A HOAX ABOUT THE 2005 CLOSE APPROACH OF MARS IS CIRCULATING ON THE INTERNET.

This hoax is on web sites (e.g., Abby's Guide: Community Discussions or Vanguard Forums) and people are also sending and resending it by e-mail.

Mars Hoax E-Mail (click to enlarge)

Many web sites exist countering this hoax including this one but this has not stopped its e-mail circulation. (Other examples include SCIENCE@NASA and Sky Insight.)

PLEASE STOP PASSING THIS RUMOR ON!

This false message about Mars resembles the following. (Many variations on this theme occur.)

The Mars Hoax Roaming the Internet

"The Red Planet is about to be spectacular!

"This month and next, Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history. The next time Mars may come this close is in 2287. Due to the way Jupiter's gravity tugs on Mars and perturbs its orbit, astronomers can only be certain that Mars has not come this close to Earth in the Last 5,000 years, but it may be as long as 60,000 years before it happens again.

"The encounter will culminate on August 27th when Mars comes to within 34,649,589 miles of Earth and will be (next to the moon) the brightest object in the night sky. It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide.

"Mars will look as large as the full moon. Mars will be easy to spot. At the beginning of August it will rise in the east at 10 p.m. and reach its azimuth at about 3 a.m. By the end of August when the two planets are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30 a.m.

"That's pretty convenient to see something that no human being has seen in recorded history. So, mark your calendar at the beginning of August to see Mars grow progressively brighter and brighter throughout the month.

Share this with your children and grandchildren. NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN"

Some of this material was essentially true—two years ago! Most data given on the close encounter relate to the close approach of Mars in 2003 but not 2005.

In 2005 Mars will be closest to Earth on October 30 (not August 27). In addition, all information on size, distance, brightness, times, etc., are left over from the close approach in 2003. This material is wrong for the 2005 close approach.

Table 1 and Table 2 give some data on the 2005 close approach of Mars. Fig. 1 (below) shows both the 2003 and 2005 close approaches of Mars to Earth. (Move cursor over image for 2003 opposition or click to see both oppositions.)

Fig. 1. Orbits of Earth and Mars. Mars is essentially closest to Earth when the "red planet" is on the opposite side of Earth from Sun (called opposition). Because orbits are noncircular (ellipses), some oppositions bring Mars closer to Earth than other oppositions (a favorable oppositions).

In 2003 Mars had a favorable opposition. In 2005 the opposition is slightly less favorable (24% further) but Mars will still be closer to Earth than it will be until 2018. (Diameters of Sun and planets exaggerated.)

[Move cursor over image to see the 2003 favorable opposition or click image to see an enlarged version of both the 2003 and 2005 oppositions.]

Mars will really only look like
an extremely bright "pinkish star"

Also, the Mars message makes the statement:

"Mars will look as large as the full moon to the naked eye"

This statement is totally FALSE.

(Click image for reality)

This misinformation may have resulted from people who did not understand the original message (and cutout some vital parts).

The disk of Mars will appear only about 20 arc sec* wide at the end of October 2005. (This about 80% as large as the 25 arc sec wide disk in 2003.) A disk 20 arc sec wide is about ninety times smaller than the apparent size of the Moon (1800 arc sec)!

*Note: An arc sec (arc second or ") is 1/3600 of a degree.

So, if one magnifies Mars about 90x with a telescope, then Mars will appear in the telescope about as large as the Moon does with the naked eye.

(In 2003, since the disk was 25 arc sec wide, one needed to magnify Mars about 75x for it to appear as large as the Moon does to the unaided eye.)

Moon and Mars

When Mars is closest to Earth in 2005, one needs a telescope with a magnification of about 90x to see Mars appear as large as the Moon does with the unaided eye.

Someone has obviously not understood this fact—that one needs to magnify Mars in a telescope to make it appear as large as the Moon.

Consequently, misguided people are propagating the myth that Mars will appear as large as the Moon!

Note: In October/November of 2005, for Mars to appear as large as the Moon does without a telescope, Mars would need to move about 90 times closer to Earth. This distance is about twice the Moon's distance from Earth (about 1/2 million mi or 800,000 km). This would be bad news for us since tide raising forces on Earth and gravitational effects on the Earth's orbit would substantially increase! At the 2005 close approach, however, Mars remains no closer than about 180 times the distance of the Moon.

Although Mars will not get as close to Earth in 2005 as 2003 (about 24% farther away), the red planet will still appear very bright and spectacular later this year. Its peak magnitude (an astronomical unit of brightness) will be about mag. -2.3. This is 58% dimmer than 2003 but still very bright, more brilliant than any nighttime star. Indeed, the only planet appearing brighter in late 2005 will be Venus.

(See Table 2 for comparison between the 2003 and 2005 close approaches.)

However, Mars will appear much higher in the sky in 2005 for northern observers compared with 2003.

This phenomenon happens because Mars will be north of the celestial equator by approximately 16 degrees in October 2005 whereas Mars was south of the celestial equator by about the same amount at its close approach in August 2003.

So, although the disk of Mars will appear slightly smaller in 2005 than 2003, many observers this year will see Mars reach a dramatically higher elevation in their sky than two years ago.

In fact, for some locations in 2005, Mars will reach an altitude above the horizon about twice as great compared with 2003. (For an example, see Fig. 1 drawn for North Florida.)

Indeed, for many people, 2005 should give earthbound observers the best views of this planet in the last fifty years and perhaps for the rest of their lives.

More material on the 2005 apparition of Mars is at:
« And read the 2006 article, The Mars Hoax Won't Go Away »