Mars has been at the center of many tall tales. Some were meant to be fiction, but others just turned out that way. Here are four Martian stories.

Percival Lowell's canals
Percival Lowell (1855-1916) was a wealthy businessman, writer, mathematician and keen astronomer. He founded Lowell Observatory in Arizona and was an influential popularizer of science.

Lowell was convinced that he could see a network of Martian canals through the telescope. In his book Mars and its Canals he argued that the existence of vegetation was the only rational explanation of the dark markings whose appearance changed at successive seasons. If there was vegetation, then surely there was animal life. Furthermore since water scarcity was a limiting factor for life, it made sense to him that advanced intelligence would try to make the best use of the water. On Mars, moving water from the polar caps to centers of population would create just the sort of markings that Lowell saw. “That Mars is inhabited by beings of some sort or other we may consider as certain as it is uncertain what those beings may be.”

The canals entered popular consciousness through Lowell's books and then via works of science fiction. Although Lowell was convinced, his arguments didn't convince other astronomers. They saw no canals, even through Mount Wilson's 60-inch telescope. Finally, in the 1960s space probes gave a definitive answer. Mariner mission photographs showed lots of craters, but no canals.

The War of the Worlds
British writer H.G. Wells's story The War of the Worlds appeared in 1897. Lowell had assumed that the Martians were peaceful and cooperative, but Wells created a tale of a horrific and brutal invasion of Earth by monstrous Martians.

Even people who haven't read the book know that Orson Welles's radio adaptation spread panic in the USA. It was broadcast for Halloween on October 30, 1938, using the format of a program interrupted by breaking news, followed by newscasters on the spot reporting the grisly events. And the ensuing widespread panic as people took it seriously? That's a myth manufactured by the press. Few people heard the broadcast, and the supposed events were unsubstantiated.

Yet on February 12, 1949 in Quito, the capital city of Ecuador, a broadcast based on the Welles adaptation had a different outcome. People left their homes. Churches opened as the end of the world seemed at hand. Crowds watched the skies as the invaders approached the city. All was confusion. When they realized what was happening, the broadcasters tried to reassure the public, and called for calm.

Although no one was hurt in the initial chaos, people were furious when they realized they'd been fooled. A mob attacked the radio station building and set fire to it. At least six people died in the rioting, and many others were injured.

A giant face on Mars?
In 1976 NASA's Viking 1 space probe photographed the Cydonia region of Mars. One image included a mesa 2 km (1.2 miles) long, looking rather like a humanoid face. The Viking chief scientist described it as a “trick of light and shadow”. Yet some people insisted it was a face and that – obviously – there was a NASA cover-up. In the years that followed, many spacecraft imaged Mars. With ever higher resolution, it became more and more obvious that the mesa was indeed just a mesa. Here's an image taken by Mars Reconnaissance Orbiter.

Humans have a talent for seeing patterns, but if it goes astray and sees patterns in randomness, it's known as pareidolia. Despite all of the photographic evidence, some people still insist that the mesa is a face created by an ancient Martian civilization.

How big does Mars look from Earth?
Mars and Earth orbit at different speeds, and although neither orbit is circular, Mars's orbit is more elongated. Thus the distance between the two planets varies widely. The closest we get to Mars is at opposition when Mars and the Sun are lined up with the Earth on opposite sides of it. The closer Mars is to us, the bigger it will look.

On August 27, 2003 Mars was closer to Earth than it had been for tens of thousands of years. Mars would have looked bigger than ever. Certainly it was conspicuous in the sky, like a brilliant reddish star. With good binoculars you could see a disk, and small telescopes showed other detail.

But an odd story about Mars began in 2003, and has reappeared almost every summer since then. You might have received it as an e-mail, or more recently seen it on social media. It always claims that you can see two moons in the sky on August 27 – whatever the year – one of them actually being Mars.

However oppositions happen every 2.13 years, not annually on the same date. And although Mars has twice the diameter of the Moon, even at its nearest, Mars is nearly 150 times farther away than the Moon. Here's a photograph of the Moon and Mars taken through a telescope by Rick Stankiewicz just over a month before the 2003 opposition.

Mars was 56 million km (34 million mi) away from us on August 27, 2003. It would have to be about 1.5 million km (940,000 mi) away in order to look as big as the full Moon.

References:
Campbell, WJ, “The Halloween myth of the War of the Worlds panic” http://www.bbc.co.uk/news/magazine-15470903
Alvear, C, “Martians Land in Quito” http://www.huffingtonpost.com/cecilia-alvear/martians-land-in-quito_b_166776.html