Mercury is the smallest planet in the solar system both in terms of mass and diameter. It is 18 times less massive than the Earth and its diameter is barely two-fifths that of the Earth. To give you a better idea of Mercury's size, let's say it's only a third larger than our Moon.
Surprisingly, this little planet has even shrunk over time. The cooling of its core caused the entire planet to shrink, reducing Mercury's volume by about 5 to 10 kilometers in radius.
When is Mercury visible in the sky?
Mercury is not easy to see. As the planet is very close to the sun, we do not often have the opportunity to observe it during the year.
The planet often comes close to the sun in the sky, and the sun's light is too bright for the planet to be visible. A little tip: The planet is most visible at great elongation when its apparent distance from the Sun is greatest.
Upcoming events
March 23, 2024: Mercury in dichotomy
On March 23, at 03:52 GMT, Mercury will reach its half-illumination phase called dichotomy. This event occurs once every 116 days and occurs around the time of greatest elongation of the planet. Mercury will shine brightly with a magnitude of -0.5 in the constellation Pisces. You'll be able to see the planet in the evening sky with the naked eye, and optical devices will offer a closer look at its half-lit disk.
March 24, 2024: Mercury at greatest eastern elongation
On March 24, at 9:59 p.m. GMT, Mercury will reach the furthest apparent distance from the Sun (18°42'). The greatest elongation is the best time to observe Mercury, because the elusive planet is not lost in the Sun's glare. The planet will glow brightly with a magnitude of -0.4. Observe it after sunset in the constellation Pisces.
