by Robert J. Vanderbei
Jupiter, Venus, Mercury, and Mars have been gracing the predawn eastern sky in recent weeks. So far I have missed out on seeing this nice conjunction due to a combination of bad weather on the East Coast and an inability to get myself out of bed before sunrise.
But all is not lost. Did you know you can see Jupiter and Venus in the daytime using a small telescope or even binoculars? Why set the alarm for 5:00 a.m. when you can sleep in and still enjoy the planets!
Last May (2010), I took the picture of Jupiter shown above in the daytime—at 9:50 a.m. local time.
It turns out that taking the picture was easy—the tricky part was finding Jupiter. Here are a few details: I used a level, a compass, and the moon to establish a fairly accurate polar alignment. Once my telescope’s mount was aligned, I could “dial-in” Jupiter’s location based on its coordinates, which I read off from the planetarium program (Cartes du Ciel) on my laptop computer.
Given accurate pointing, it was easy to find Jupiter in a low-power eyepiece. I was even able to see Jupiter’s cloud bands. But I didn’t notice the Great Red Spot or Jupiter’s moons Io and Europa until I stacked and sharpened the images I acquired as video using a webcam. Next time, I will make sure to check if they are visible as I look through the eyepiece.
Here’s a picture of the setup. I used an inexpensive webcam (a Philips ToUcam) attached to my 3.5-inch reflector, made by Questar. Note that for safety I positioned my equipment in the shadow of my house, so that I didn’t have to worry about inadvertently pointing the telescope at the sun.
Here’s a shot of the setup from a different angle. You can see the live video of Jupiter as it was being displayed on the computer screen.
You can also take daytime pictures of Venus. Here’s one I took at 3:48 p.m., just five days before a conjunction on March 21, 2009. Notice that, like the moon, Venus goes through phases and can appear as a crescent when seen through a telescope.
Robert J. Vanderbei is chair of the Operations Research and Financial Engineering department at Princeton University and co-author of the National Geographic book Sizing Up the Universe. Vanderbei has been an astrophotographer since 1999, and he regularly posts new images on his astro gallery website.