Mars is now at its closest to Earth since Neanderthals walked the planet.

As of August 27, the Red Planet will be a galactically trifling 55.76 million kilometres (34.65 million miles) from Earth, according to Belgian astronomer Jean Meeus, who calculated the two planets last came as close nearly 60,000 years ago.

The fourth planet from the Sun, Mars will appear red and orange and as bright as Jupiter, the giant of our solar system as the Red planet has a rare orbital rendezvous with the Earth.

Amateur and professional astronomers flocked to some 300 observatories across Japan, while others set up telescopes away from the urban neon glare in the country and on rooftops.

Some 800 were expected at the Nishi-Harima Observatory in Hyogo prefecture, western Japan, to take part in the "Mars Observation Show."

"People's interest in Mars is reaching its peak as some people are increasingly speculating on the existence of life on the mysterious planet," said Noritaka Tokimasa, an astronomer at the observatory.

But many people were disappointed as broken cloud covered much of central and western Japan including Tokyo, although skies were clear in northern Japan and in Okinawa in the extreme southwest.

"The weather conditions are perfect as we can observe Mars shining clearly in the dark sky," said Seiichi Hirano, an astronomer at Sapporo Starlight Dome observatory in Sapporo, on Japan's northernmost island of Hokkaido.

"We are glad some 300 visitors who gathered today can share this historic moment," Yasutani said.

In Sydney, thousands of amateur and professional stargazers also turned out across Australia to get an historic peek at Mars, some hoping the once-in-60,000-year glimpse might give a hint of life on the Red Planet.

Scientists from the Australian National University were hunting from their Siding Spring Observatory in New South Wales state for signs Mars may have once been able to support life.

"We have better telescopes set up to look at the chemistry of things, and maybe, just maybe, we might get an observation from somewhere that shows indications that the chemistry necessary for life may have been there at some stage," said ANU astronomer Vince Ford.

But even if no signs of life emerge, Ford said Wednesday's close-up look at Mars would be memorable.

"It's nice to say, the last time this happened probably Neanderthals were looking at it, and this time it's me," he said.

Thousands of people were expected to turn out in Melbourne, at Sydney's Observatory and in parks around the country.

In Singapore, a spokesman for the Singapore Science Centre said scientists would be observing the Mars phenomenon at the observatory on Wednesday evening but no special events had been organised.

However, the Science Centre Observatory, that houses Singapore's most powerful telescope, will be open for public viewing of the night sky.

Members of The Astronomical Society of Singapore were due to bring along their own telescopes to share with the public and to provide information on the Mars phenomenon.

In Bangladesh several hundred people crowded the Wonderland Park in the capital Dhaka early Wednesday ready to have look at Mars through a recently imported telescope.

Similar arrangments have been made by the Bangladesh Astronomical Association and the National Science and Techology Museum.

With the rainy season in full swing in Thailand and storms battering Bangkok most afternoons, there were fears there that poor weather could prevent Thais from getting a good look at Mars.

Even so, crowds gathered early at the Science Ministry to catch a glimpse of the spectacle through the three telescopes and large projectors installed for the public.

SPACE.WIRE