What can you do with a really cheap camera and a basic telescope? You can get a video of Jupiter and its moons! You can even record the magnitudes of those moons.
Click here for a series of posts on “Affordable Astronomy”. These posts all center on astrophotography done with a $10 smart phone, bought almost ten years ago at a grocery store, that I call the “Ten Buck Wonder”, or TBW. In other words, astrophotography with an old, cheap, junky phone. The bottom line is that we all can try our hands at astrophotography — we do not have to have a lot of money to do it.
To take video of Jupiter, I used the TBW, a telescope I have assembled from a couple of other telescopes, and a cardboard-and-rubber band “camera mount” to hold the camera to the telescope. I shot the video below on the evening of November 6, 2022. (I shot a good bit more video than this, and then clipped one of the better parts to make this video.)
A couple of things stand out in this video. First, you can’t see any detail on Jupiter. It is just a big glowing ball. By contrast, it was pretty easy to see the planet’s cloud bands just looking through the telescope alone, with no camera. The TBW could not deal with the darkness of the overall scene and the brightness of Jupiter, and so all detail on Jupiter was washed out.
But the second thing that stands out is that you can clearly see the moons. With a free app like Stellarium, we can easily identify the moons, once we realize that the view through the telescope is reversed. See the video still image and the screen shot from Stellarium below. The moons are, from left to right, Europa, Io, Ganymede and Callisto.
If we reverse the telescope image, and adjust both the telescope image and the Stellarium image to scale, we can see that both are really in very good agreement. We can even overlap the two images and see how good the agreement is! We can certainly see how washed-out Jupiter is, and thus better understand why we cannot see any cloud bands on its surface.
Note how dim the moon Callisto appears in the telescope images. The Stellarium image does not show this. Stellarium is pretty bad at showing brightness. However, it has a feature that allows us to look up the “magnitude” of each moon. (Remember that magnitudes are like rankings — being #1 is better than being #2, which is better than #3, etc.; a bigger number means less bright.)
That feature gives the following numbers: Europa is magnitude 5.5; Io, 5.4; Ganymede, 4.9; and Callisto, 6.2. Callisto is indeed significantly dimmer than the other three. Ganymede does not look brighter in the still image, but I think it does look brighter in the video. And, in the video, Callisto fades out, and is hardly visible for most of the video (maybe some very thin clouds entered the view).
The third thing that stands out in the video is that Jupiter and the moons are moving. That is on account of the Earth’s rotation. My cheap telescope does not have a motorized mount that tracks celestial objects. I have to keep adjusting the thing by hand.
But I can live with those hand adjustments and my junky camera. I can do some fun stuff with this very basic equipment! (Like the cardboard and rubber-band camera mount that is holding the TBW to the telescope in the photos below).
