There are always at least few comets visible in the sky. Usually there is one large enough comet to be visible in binoculars and others tha can bee seen with telescope. Once every few years there can be comet visible with naked eye.
At the moment we have also a little bit unusual scenario – in the morning sky in northern hemisphere we can see three comets with binoculars! These are comets: C/2012 S1 (ISON), 2P/Encke and C/2013 R1 (Lovejoy). Last night (actually today morning) I spent some time on imaging all of them.
2P/Encke has the shortest period of any known comet – it completes the orbit every 3.3 year. Its nucleus diameter is 4.8km. Encke comet orbit is unstable and evolves over time due to perturbations and outgassing. The picture has been shot at 04:27 CET and the exposure time was 5×60 seconds. The comet in this moment was about 80mln km from Earth and its velocity was 46km/s. At this distance the pixrel scale is about 950km/px (when enlarged).
C/2013 R1 Lovejoy is quite new comet discovered on September, 9th. This comet will pass its perihelion on December, 25th. The picture below was shot at 3:55 CET and exposure time was 5×90 seconds. The Lovejoy comet was 110mln km away at this moment and traveled across Solar System with velocity 38km/s. Piksel scale is about 1300km/px (when enlarged).
C/2012 S1 ISON comet is probably the most famous comet this year. It was discovered on Septermber 21st, 2012. The comet will pass its perihelion on November 28th, 2013 in a distance only 1.9mln km from the Sun center that is only about 1.2mln km over the Sun surface! At the end of this year the comet may become visible with naked eye under the dark sky. Currently its magnitude is about 9mag, so it is binocular target. The picture belowe has been shot at 4:11 CET with total exposure time 10×120 seconds. The comet was at this time about 200mln km away from Earth, so the picture pixel scale is about 2400km/px when enlarged.
One may wonder what the heck are these lines at photos? These are star trails – during the exposition time the comets moved significantly across the sky. So we could track the stars and have comet blurred or we could track the comet and have star trails. In this case the answer was simple 🙂