Mars has had a close encounter with Earth, approaching to within 69.4 million km (43.1 million miles) of our planet in the early hours of Sunday.
Mars will not be as close to Earth again until 2018
Conditions were cloudy over most of the UK, meaning amateur astronomers had difficulty seeing the planet.
Mars will not swing this close to Earth for another 13 years.
Astronomers in the south east or north west of the country would have had the best chance of seeing Mars, the BBC Weather Centre said.
Observers with more powerful instruments would have been able to see much more detail on the surface.
Dr Robert Massey, an astronomer at the Royal Observatory, said those who missed Mars on Sunday should not be disappointed - the planet will still be visible for "at least the next couple of months".
He said the planet was easy to distinguish because it had a reddish tinge and a sustained light, as well as appearing larger than neighbouring stars.
Dr Massey said the planet's close position to Earth was a boon to astronomers.
He said: "The closer it is to Earth, the bigger it is, and hence the more detail you can see."
He said in recent times, "there's more and more evidence to suggest Mars was once a warm and wet place, albeit only briefly.
"There probably was an epoch in its history, we don't know for sure whether there was life there, but certainly the conditions would have been OK for it."
In August 2003, the Red Planet made an even closer approach to Earth, when it was at its nearest for about 60,000 years at a distance of 55.6 million km (34.6 million miles).
But Mars is higher in the sky this time than in 2003, meaning that the planet's light is not affected as much by the Earth's atmosphere. This makes for better viewing in the Northern Hemisphere.
Peter Bond, of the Royal Astronomical Society, told the BBC News website on Saturday the best views of the Red Planet would be found out in the countryside, away from street lights.
Through small and medium-sized telescopes, Mars appeared as a small, luminous ball in the east before midnight, reaching its highest point in the sky after midnight, then setting in the west.
He added amateur astronomers might be able to see Syrtis Major - a dark, triangular patch on the Martian surface near the equator - in the coming weeks. The planet's southern polar cap might also be visible through telescopes.
But Mars is also going through its southern summer, with an accompanying increased risk of dust storms. This means surface features could be blotted out.
The Red Planet reaches opposition - when it is directly opposite the Sun in the sky - at 0820 GMT on 7 November.
Mars will then rise in the east at sunset, reaching its highest position in the sky an hour after midnight.
Earth and Mars are separated by an average distance of 225 million km (140 million miles).