The perfect time to spot Mercury is next Thursday

Next Thursday, Mercury reaches its greatest eastern elongation. The smallest planet in the solar system will be more than twenty-seven degrees away from its parent star, as seen from Earth. This particular evening apparition is, by far, the best of the year for southern hemisphere sky watchers. If you want to spot the innermost planet, the next week is the perfect time.

So, how do you find Mercury? With the Sun setting just after 5:30pm and Mercury dipping below the horizon at around 8pm, there’s a brief window of opportunity each night to catch the planet. An hour after sunset is about the best time to look. By then, the sky will be relatively dark, and Mercury’s altitude will still be more than 10 degrees.

This evening, Venus can be a guide to help locate Mercury. Venus will be visible as a blazing "star" very low in the West. Just to the right, you should be able to see Regulus, the brightest star in the constellation Leo.

Once you have found Regulus, cast your gaze up and slightly to the right. Mercury should be visible as a pinkish-coloured object some thirteen degrees above the horizon. That’s about the same angle as that subtended by your index finger and little finger at arm’s length. If you have a telescope, you will need a reasonably high magnification to see Mercury’s tiny disc. The planet will be 56% illuminated, resembling the gibbous moon.

Mercury is fascinating. Its proximity to the Sun results in extreme conditions, with daytime temperatures soaring to 427°C while at night, temperatures plummet to -180°C. Its surface is etched with ancient lava flows, impact craters, and mysterious "hollows". Mercury has a unique orbital resonance, completing three rotations for every two orbits around the Sun.

Regarding upcoming space missions, NASA’s BepiColombo is a joint mission with the European Space Agency, launched in 2018. It will reach Mercury in 2025, deploying two orbiters to study the planet’s surface, magnetic field, and interior structure. This mission promises to revolutionise our understanding of the solar system’s innermost planet.