In the eastern U.S., Venus and Jupiter will appear to be only a third of a degree apart from each other, and their starlight will join together to form a visual effect of a double star.

The effect will appear to be just .2 degrees apart in Europe, making it look like they are touching each other.

This phenomenon is known as a conjunction, and can be best seen around 30 to 60 minutes before sunrise.

An ideal viewing spot would be in a flat, open location unobstructed by tall buildings or trees.

To enhance your view of the planets, try using a pair of binoculars or a telescope. If the sky is still dark enough to see stars, locate the constellation known as the Beehive Cluster.

The two planets should appear below that group of stars, according to NASA.

 "They will be so close together that it's going to be quite a striking sight.

"Undoubtedly people could mistake them for a UFO, especially being so low down," said Robin Scagell, vice-president of the Society for Popular Astronomy, according to AAP "They might appear to move around because of the distortion effect of the atmosphere."

Clouds will make it hard to see the effect, so make sure to check the weather before waking up early on August 18 when they will appear to be closest together.

They will continue to move towards each other over the next three days, and can still be seen close together from Earth, according to NASA. Then they will start to move apart again.

Jupiter and Venus don't cross paths very often, usually about once a year, but usually at a more removed distance from each other.

It will be the closest conjunction of Jupiter and Venus since 2000.

Venus will seem much brighter than Jupiter as it comes closer to the Earth, despite the fact that Jupiter is much larger. Venus is lit up more intensely since it is closer to the Sun.

The next Venus-Jupiter conjunction is due to take place on June 30 next year, but it won't be as close, according to NASA.

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