JUPITER WITH SATELLITES

2015 February 21, 8:52 p.m. EST (Feb. 22, 01:52 UT)
Rosemary Hill Observatory • Bronson • Florida

Brief Object Notes: Except Venus when near Earth and showing a large crescent, Jupiter exhibits the largest disk in earth-bound telescopes of any planet, sometimes approaching 50 arc seconds across! No other planet reveals as much detail even in small telescopes as this giant planet. Of course, its four large satellites are also easily seen (assuming not in transit or occultation). Jupiter, the solar system's largest planet, is 11 times the diameter of Earth orbiting 5.2 AUs from the Sun. (At the time of this photo, Jupiter was 4.4 AUs from Earth with light taking 36 min. to reach Earth.)

Photo Notes: Although Jupiter's equatorial diameter in the photograph is 45 arc seconds across (30-45 arc sec is typical), photographing this planet with a short focus 5-inch (focal length 660 mm) telescope is challenging even with a 4x amplifier. (Effective focal length is still only 2,640 mm.) Here Jupiter's image size in the focal plane was only about 0.6 mm wide! Ideally, longer focal lengths are better for larger image sizes.

During imaging, Jupiter's disk trembled from poor seeing and exhibited large variations in brightness due to passing clouds and haze. Trying to establish a proper exposure and good focus was a challenge! Although the planet was near greatest brilliancy (mag. -2.5), its disk would sometimes become almost invisible. Still, the photo below, taken under these poor seeing conditions with variable haze and clouds, reveals what a keen observer can often see.

Note the observational challenges listed below show what patient observers might see when observing Jupiter. Can you make out these features in this photo? (Be sure to view the larger image.) In fact, although this photo was taken with only a 5-in. aperture telescope under poor viewing conditions, nearly all of the features listed can be seen in this image.

PUT CURSOR OVER IMAGE FOR LABELED VERSION — ALSO CLICK IMAGE TO ENLARGE

Photo Details 2015 Feb. 21, 8:51 p.m. EST TeleVue 127 mm, f/5.2 APO Refractor, Foc. Len. 660 mm w/Televue 4x Powermate (Effec. Foc. Len. 2,640 mm) Camera: Canon DSLR EOS 5D II Separate Images of Disk & Satellites Combined Exposures: Disk 1/180 sec & Satellites 1 sec (both @ f/21, ISO 1600)

OBSERVATIONAL CHALLENGES Can You See: Four Galilean Satellites Two main Equatorial Belts Temperate Belts near Poles Polar Hoods (Darkening) Great Red Spot (not turned toward Earth in this photo) Oblate Shape (Jupiter is not round!) QUESTION: How oblate is Jupiter? Oblateness is a measure of "roundness," i.e., having Equatorial Diameter greater than Polar Diameter Definition of Oblateness: Oblateness ≡ (Eq. Diam. - Pol. Diam.)/Eq. Diam. Do This: Use a ruler to measure diameters on your monitor. (First, click image to enlarge.) Calculate oblateness. Express answer as reciprocal Do it carefully. Did you get correct result? I did! ANSWER HERE

« RETURN TO THE MAIN RHO PICTURE PAGE »

RETURN TO PLANET CATEGORIES

RETURN TO PICTURE CATEGORIES

Images © 2004–2015 H.L. Cohen
Email Cohen followed by @astro.ufl.edu
Last updated 2015 May 18