Jupiter and Venus will align almost completely on Monday night

The closest conjunction of Venus and Jupiter since 2000 will be visible from even fairly low vantage points

Look up. A flurry of UFO "sightings" is expected early on Monday morning when a spectacular "double star" is created as the two brightest planets in the sky align almost completely.

In what is said to be one of the highlights of the astronomy calendar this year, the conjunction of Jupiter and Venus will be visible shortly before sunrise at 5am on the north-east horizon.

They will appear to be only 0.2 degrees apart, less than half the width of a little finger when held out at arm's length.

"They will be so close together that it's going to be quite a striking sight," said Robin Scagell, vice-president of the Society for Popular Astronomy.

"Undoubtedly people could mistake them for a UFO, especially being so low down. They might appear to move around because of the distortion effect of the atmosphere."

It will be the closest conjunction of Venus and Jupiter since 2000 but although the planets appear to be kissing-distance apart as seen from the Earth, they are separated by hundreds of millions of miles.

Venus and Jupiter pair up about once a year on average, but their conjunctions vary greatly in separation and visibility. Some are missed completely because they occur in daylight.

The next conjunction between the two planets is due to occur on 30 June next year, but will be less close.

During Monday's conjunction, Venus will appear six times brighter than Jupiter even though its diameter is less than a tenth that of the larger planet, which measures 86,881 miles across.

That is because Venus is much closer to the Earth and also nearer the Sun, causing its clouds to be lit more intensely.

Those hoping to get the best experience from the conjunction have been advised to use a pair of binoculars or a small telescope to get a dramatic view and watch it from a high unobstructed vantage point.

Venus will mimic a tiny full moon, while Jupiter appears three times wider. Jupiter will also be accompanied by its four brightest moons strung out in a row.

"People who have buildings, hills or trees in the way might miss it, but even a rooftop in London should offer a good view," said Scagell.

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