January 6th, 2009


Astro-Image of the Day: Jupiter Eclipses Ganymede

What a dramatic shot! In this Hubble Space Telescope photo, you see Jupiter just beginning to eclipse its moon, Ganymede.

Click the image to see the story.

To see how hazy Jupiter's upper atmosphere is, astronomers used the Hubble to take this photograph. It's a rare image because even though Ganymede's orbit around Jupiter takes only a week, its orbit is tilted such that it usually passes above or below Jupiter.

Because they used the powerful Hubble, we get to see a myriad of storms throughout Jupiter's bands - and the Great Red Spot - plus many dark features on Ganymede's icy surface. However, because Jupiter is one of the brightest objects in the sky and Ganymede is a very large moon, anyone can witness such an event with a small telescope or even a pair of binoculars! Just don't expect to see this level of detail *g*

Speaking of home telescopes, next up come my first astrophotos taken with my telescope and astro-camera....


Bonus Astro-Image of the Day: A Flight over the Moon

I made this animated GIF from a series of astro-photos I took using my Meade 12" LX90 GPS telescope and a Meade DSI-III astro-imager, then reduced the image size and pumped them through an animated-.gif maker (free version, hence the silly "Trial Version!!" banner).

Because my telescope's drive appears to think it's on the Earth's Southern Hemisphere, so the drive isn't tracking correctly. Ironically, even though this makes taking astrophotos a pain in the buttocks, the movement inspired me to make this into a single GIF. Feels like a flight over the Moon!

EDIT: Optics details: This image was taken at prime focus (no eyepiece) through an f/6.3 focal reducer, resulting in a focal length of 76.8" or 1951mm. Without the reducer, this telescope is an f/10, giving it a focal length of 120", which would increase magnification even more (at f/6.3, the Moon more than fills the field of view at prime focus).

Images are less than 1 second each; not sure exactly how long (I'll pay closer attention next time - was distracted by the combined image looking so blurry), nor of the interval between them. Say, 1/10 second each with an interval of a few seconds?

Next time I'll also use a polarizing filter to help reduce the over-bright areas, and adjusting the clock drive will allow me to combine images for greater sharpness. Here's a still from the animated GIF (under the cut):

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