Jupiter + Saturn
Jupiter and Saturn Conjunction 2020
Jupiter and Saturn approached each other on the evening of Sunday, December 20, 2020, and this image would represent their closest approach with clear weather and visible from my observatory site. Jupiter displays its giant red spot clearly as well as the four Galilean moons, collectively named after their discoverer, Galileo. Saturn is 10 times fainter than Jupiter so has been enhanced in this image to make it approximate Jupiter's brightness. Likewise, the moons of both Jupiter and Saturn are from 40 to 10,000 times fainter than Saturn and have also been enhanced to bring them to visibility. Jupiter is about 90,000 miles in diameter and could hold approximately 1000 earths. Saturn is only 72,000 miles in diameter, however its rings extend another 100,000 miles further at about 175,000 miles in diameter. Jupiter is about 1/2 billion miles from earth, but Saturn measures in at a whopping 1 billion miles away, hence its faintness and smaller apparent size. Notice how Jupiter's moons appear all in a line, but Saturn's seem to surround it. This is due to Jupiter's inclination of its axis by only 1 degree, consequently, there are no seasons, and we always see the moons in an edge-on plane. Saturn's axis inclination, however, is almost 27 degrees, and like earth, it has seasons, albeit 7 years long and certainly strange compared to earths. During this image, a combination of 7 each of red, green, and blue filtered 4/100s exposures were used. The two planets were 7.5 minutes of arc apart or 1/4 the diameter of the moon. Later in the evening but after setting, they would get as close as 6 minutes of arc or 1/5 the diameter of the moon. At the time of this image, 6:04 pm Central Time, they were only 20 degrees off the horizon hence the lower sharpness and clarity. Also note there was a 7.5 magnitude star GSC 6323:2045 in this image but since the telescope was locked in on the combined slow movement of Saturn and Jupiter, the star blurred and was averaged out of the image. Click on the image for a larger, full screen view.
Optics: RC Optical System 20" F/8.2 (4165.6 mm Focal Length) Date: December 20, 2020
Camera: SBIG STXL-11000 at prime focus Location: Columbus, Texas
Exposure: RGB = 7x0.04:7x0.04:7x0.04 seconds Imager: Kent E. Biggs