Comet Encke is a periodic comet that completes an orbit of the Sun once every 3.3 years and makes a close approach to Earth every 33 years. This week it has been visible through the eyes of the SOHO solar observatory as it swings around the Sun. It made its closest approach to the Sun (perihelion) on March 10, 2017.
Normally, a comet has two tails: an ion tail of charged particles emitted by the comet and pushed out by the wind from the Sun, and a dust tail of small debris that orbits behind the comet but is also pushed out, to some degree, by the solar wind. Frequently a comet appears to have only one tail because the other one is not easily visible from Earth. However on February 20th NASA's Astronomy Picture of the Day showed an unusual image of Encke sporting three tails, because the ion tail split just as the photo was being taken. The complex solar wind is occasionally turbulent and sometimes creates unusual structure in an ion tail. On rare occasions,ion-tail disconnection events have been recorded.
This comet was first recorded by Pierre Méchain in 1786, but it was not recognized as a periodic comet until 1819 when its orbit was computed by Johann Franz Encke, thus giving it its name. Its nucleus has an estimated diameter of 4.8 km (3 miles).
Credit for Image at Top of Page:
“Comet 2P/Encke swings by the Sun - March 2017.” Credit: NASA/ESA LASCO C3