A big story lately in the astronomy community has been the passage by the Earth of Comet 46P/Wirtanen. The comet was discovered in 1948 by the American astronomer Carl A. Wirtanen of Lick Observatory. It has a period of orbit around the Sun of 5.4 yrs. What makes it so noteworthy now is how close it has come to the Earth, about 30.1 times father than our Moon. This image shows the comet’s orbit as an elongated light grey ellipse. The orbit is tilted slightly with respect to the plane of the inner planet orbits. Earth’s orbit is the 3rd one out from the Sun in light blue.
The orbits of Earth and Wirtanen brought them close together during the middle of December 2018. Because of the timing of the orbits of each, they will not have another close encounter for another 20 yrs. I used the JPL Small-Body Database Browser to view an animation of the orbits. This video screen grab shows Wirtanen between 1 Sep 2018 and ending 1 Feb 2019.
Amateur and professional astronomers took advantage of this close encounter opportunity to gather data and capture many images. The Virtual Telescope Project directed by Gian Masi provided an online viewing opportunity from their observatory in Italy. Over the course of 70 min on 18 Dec 2018, their system tracked 46P as it moved across the field of stars. The actual movement of the comet is compressed into 25 seconds.
Dr. Brian May, astrophysicist and former lead guitar player for the rock group Queen, posted this on Instagram on 18 Dec 2018. Two images of comet 46P were taken by Jamie Cooper 70 minutes apart. May arranged them side-by-side so the viewer can see the comet in 3-D.
Viewing can be done in either of two ways. The first image below requires the parallel viewing method. Stare straight ahead through the images as though you are looking at a distant object through a window. Let the images merge into a third one in the center. It should appear three dimensional with the comet in front of the star field.
If parallel viewing doesn’t work for you, use this next image viewed cross-eyed. I reversed the images used above. Let the images merge into one in the center for the 3-D effect.