Saturday, August 27, 2016

Jupiter Venus Conjunction

Today was the occurrence of a very tight conjunction of Jupiter and Venus, the two brightest planets in the sky. Phil Plait has an article on the conjunction on his Bad Astronomy blog. The position of Venus is predicted to be visually closer to Jupiter than the outermost moon Callisto. This tight of a conjunction is a rare event and I did not want to miss it. Unfortunately, the day was very cloudy and I feared I would see nothing. Just before sunset, I headed out with the camera to a spot near home where I could observe the western horizon. The sky was indeed hazy with broken clouds but there looked to be a chance of seeing something so I set up for the show.

I watched the sun pass behind a bank of clouds and set. A very nice view.

After the sun set, I began to anxiously scan the sky for the planets, both below and above the cloud bank. I finally spotted a dot under the cloud bank and took many pictures of it. Humm, I expected Venus to be much brighter but maybe it was the haze ... also, there should have been two dots very close. I started convincing myself that I had not done the field-of-view calculations correctly and that the planets were so close that I could not resolve them. I saw nothing else around so I packed up and drove towards the grocery store.

As I did so, I looked back over my shoulder and saw a clear conjunction higher in the sky peeking out of the clouds ... how embarrassing. I found another place to observe and took more pictures. These next two images, taken at a 190mm and 250mm focal length and about 15 apart, show Venus upper most and Jupiter just below and to the right. This was indeed a spectacularly close conjunction. I had hoped that the third dot was Mercury as this was its expected relative angle to the other two planets. Mercury, however, is much further down near the horizon and behind the clouds. This third dot is actually the star Zavijah (β-Virgo).

Zooming in to a 560mm focal length and cropping, we can see the moons of Jupiter. The three in a row are Io, Ganymede, and Europa. Further out, dimmer, and just below Venus is Callisto. Two hours earlier, Venus would have passed just to the upper right of Jupiter, closer than Callisto. No chance of seeing that closest approach from Texas as the sun was still bright in the sky.

I am glad I saw the real conjunction after all. I am still not sure what star I was staring at initially.

No comments:

Post a Comment

Relevant comments and questions are welcome but submissions with spam-links will not be published.