Early-rising stargazers get to witness something rather exciting before sunrise tomorrow. In an event astronomers call a planetary conjunction, Mercury and Mars will appear very close together in the sky. At the moment of closest approach (which occurs at 6am when the sky will be too bright to spot them), the planets will be separated by less than a quarter of a degree. That’s less than half the size the full moon appears in the sky. While Kiwi skywatchers won’t be able to see the precise moment of close approach, the two planets will still be beautiful as the sky brightens tomorrow morning, so it is worth getting up early.
The best way to find Mercury and Mars is to use Venus as a jumping-off point. This week, all three planets are moving through the constellation Sagittarius. Venus rises at 3.50am and is just to the right of the famous "teapot". The second planet from the sun is blazingly bright and will be some 15 degrees above the horizon by 5.30am. Once you locate Venus, cast your gaze down and to the right. You should be able to spot Mercury as a pinkish "star" at an altitude of six degrees. Mars will be much dimmer than Mercury and visible slightly above it. Mercury and Mars rise at around 4.40am, so if you want to catch them before the sky gets too bright, you will have to find a spot with an unobstructed eastern horizon.
Of course, while Mercury and Venus appear close together, in reality, they are separated by millions of kilometres, as this week’s second chart shows. That’s because when we gaze up at the sky, what we perceive as a two-dimensional image is, in fact, a projection of the three-dimensional universe on to the celestial sphere. The inherently three-dimensional universe extends pretty much infinitely in all directions, yet our perspective from Earth yields a flattened representation when we gaze at the heavens. In essence, our perception of a two-dimensional sky conceals the intricate, multidimensional dance of celestial bodies that exist in the boundless expanse of the cosmos.
