This Saturday morning (the 10th) I will be on the BBC talking about comet Lovejoy, which is currently visible to the naked eye. This comet, more correctly known as C/2014 Q2, was discovered on the 17th of August last year by Terry Lovejoy. According to wikipedia, this is the 5th comet discovered by Lovejoy and he discovered it using a 0.2m Schmidt-Cassegrain telescope, which is not a particularly large telescope.
Comet C/2014 Q2 is just passing from the not very well-known constellation Eridanus (which is just to the South-West of the much better-known constellation Orion) into the constellation Taurus. Tomorrow (the 9th of January) it will cross the celestial equator, and so moves into the northern-half of the sky making it more visible to observers in the Northern Hemisphere. Below is a chart of its motion through the constellations between December of last year and January of this year. According to the comet’s ephemeris, it will pass from Taurus into Aries on the 22nd of January, and into Andromeda at the beginning of February.
C/2014 Q2 is a long-period comet, it has been calculated that its period is about 11,000 years! Unlike short-period comets which come from the Kupier belt, such long-period comets come from the Oort cloud. I mentioned the Oort cloud, which has never been directly observed, in this blog here. As the diagram I showed there illustrates, it is believed to be a spherical cloud many thousands of Astronomical Units (AUs) away from the Sun, and hence comets from it can come into the Solar System at any angle. Comet C/2014 Q2 is coming in at a very steep angle to the Solar System, some . The comet was at its closest to the Earth yesterday (the 7th of January), when its distance from us was only 0.47 AUs, just under half the distance from the Earth to the Sun. It will reach perihelion (its closest to the Sun) on the 30th of January, when it will be 1.3 AUs from the Sun.
Comet Lovejoy should be visible to the naked eye over the next week or two, even if you don’t happen to live in a rural location. It should be at its brightest over the next week to ten days, reaching a peak brightness of nearly 4th magnitude, and remaining brighter than 5th magnitude until the end of January. As its location in the sky is so easy to find (you just need to find Orion and then – as seen from the Northern Hemisphere – go up and to the right from there), it should be a rare opportunity to see a naked-eye comet. So, make the most of these long winter nights and try to spot this comet in the evening sky!