At 1.23am, when the moon is a mere one-and-a-half degrees above the horizon, a green "star" will appear from behind the moon’s dark upper limb, taking several seconds to become fully visible. That star is actually the planet Uranus. The seventh planet from the sun will be emerging from an event astronomers call an occultation.
Occultations occur when a closer celestial object passes in front of one which is further away. While the moon is a mere 390,000km from Earth, the distance to Uranus is almost three billion kilometres.
To be honest, given the low altitude, this particular reappearance of Uranus from behind the moon will be incredibly difficult to observe. That being said, even if you miss the end of the occultation, all is not lost.
If you have not seen Uranus before, its close proximity to the moon on Friday morning offers an excellent opportunity to find it and add it to your planetary bucket list. The separation between Uranus and the moon will gradually increase as they rise in the sky. They move apart because of the moon’s orbital motion around Earth.
If you know where to look, Uranus is easily bright enough to be seen with the unaided eye from a dark site. However, the proximity of the bright lunar disk on Friday means you will probably need a pair of binoculars to be certain of spotting the gas giant planet.
At 2.30am (the time this week’s chart is drawn) the red planet Mars will be visible below and to the right of the moon. The moon and Uranus are located in the outskirts of the constellation Aries.
Mars is in the neighbouring constellation of Taurus.
Once you spot Mars, look below and to the left. The star cluster Matariki will just be clearing the northeast horizon, making for a very pretty celestial scene.
