Mercury’s transit across SunDate: 12 November 2019 Tags: Space
On November 11, the planet of Mercury skipped across the vast, glaring face of the sun in a rare celestial transit.
Mercury is the solar system’s smallest, innermost planet. The next transit isn’t until 2032, and North America won’t get another view until 2049.
During this transit of Mercury, the innermost planet spent about 5.5 hours crossing in front of the sun from our perspective on Earth. Skywatchers across the Americas, Africa and Europe could see at least part of Mercury's journey across the sun.
Transits of Mercury are relatively rare events, with about 13 happening every century, on average. The last Mercury transit was on May 9, 2016, and the next one will be on Nov. 13, 2032.
Reason for transit
Mercury and Venus are the only two planets that can transit the sun from Earth's perspective, because they are the only planets whose orbits are closer to the sun than Earth's.
These transits happen because the planets' orbits are slightly tilted to the ecliptic, or the plane of Earth's orbit, and those orbits intersect at two places called "nodes."
Transits occur when Earth crosses a node at the same time as the other planet. In Mercury's case, this always happens in May or November. For Venus, transits occur in June and December.
When Mercury passes in front of the sun, scientists can observe changes in sunlight that passes through its tenuous atmosphere, allowing them to study its elemental composition.
Mercury is the smallest and innermost planet in the Solar System. Its orbit around the Sun takes only 87.97 days, the shortest of all the planets in the Solar System.
Two spacecraft have visited Mercury: Mariner 10 flew by in 1974 and 1975 and MESSENGER, launched in 2004, orbited Mercury over 4,000 times in four years before exhausting its fuel and crashing into the planet's surface on April 30, 2015. The BepiColombo spacecraft is planned to arrive at Mercury in 2025.