Jupiter Daytime View | 21 Apr 2022

Two days ago, I viewed Venus as it crossed the meridian to the south at 10:26 am. I attached an old smart phone to the eyepiece in order to confirm settings and setup. It was an easy target. Image quality was not very good. But, it worked.

Venus @ 10:26 am 19Apr2022

I tried to image Jupiter as it passed the meridian at 11:00 am and didn’t succeed. I could see it with my naked eye. But the camera didn’t capture it. Removing the phone adapter to look through the eyepiece and then returning it for an image disturbed the alignment.

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Venus Saturn Mars

Venus has been a prominent early morning sight for several weeks. If you are an early-riser and look low toward east, you can’t miss it. It will be there until late summer or early fall. Less obvious in the same part of the sky are the planets Saturn and Mars. On 28 March 2022, the clear predawn sky even presented a thin crescent Moon below this grouping of those planets.

On successive mornings, Saturn and Mars approached closer to each other. This view on 3 April 2022 was photographed through a living room window. The green thing is a glass ornament. This was the only unobstructed viewpoint due to trees and rooftops.

3 April 2022 at 6:14 am

It was a rainy morning on April 4. But, the sky was mostly clear on the 5th. Saturn and Mars were at their closest approach less than the diameter of a full moon.

5 April 2022 at 6:00 am

Keep watching that part of the sky to the lower left of Venus. Jupiter will begin making an appearance. On 18 April 2022, these four planets will form a straight line like this.

18 April 2022 at 6:00 am

Angle of Sunlight Over Time

I conducted a long series of observations for nearly 4 months. No scientific discoveries were expected. I was just curious.

We have a window that faces south. In the summer months, the roof overhang blocked the sunlight from shining through the glass. Starting about September 1st, the lower elevation angle of the Sun at noon allowed it to shine onto the floor. As the weeks passed, the shadow of the window sill moved farther from the wall. I found a long strip of paper to record the edge of the shadow of the sill at various dates. This image illustrates the sunlight paths for the 1st of Sep, Oct, Nov, and Dec.

Light rays over the window sill at the four selected dates.
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Galilean Moon Events | 15 Aug 2021

The four largest moons of Jupiter are Io, Europa, Ganymede, and Callisto. First seen by Galileo Galilei in December 1609 or January 1610, he described them as satellites in orbit of Jupiter in March 1610. They are easily seen near the planet using a simple telescope or a steadied pair of binoculars. They are currently well placed with Jupiter in the evening sky to the southeast soon after sunset.

Imagine being high above Jupiter looking down at the planet and the four moons. Desktop planetarium software is very helpful here. In this view, Jupiter is centered. The Sun is far to the left off-screen. The moons are labeled in each of their orbits. The fastest is Io closest to Jupiter. Callisto is the slowest. Three of the moon have shadow lines drawn in orange. Play the video and watch their movements. The shadows cast by each of those three moons are intercepted by Jupiter. The software speeded up the rate many times.

What would this event look like for viewers on Earth? Earth would be located far off-screen to the left toward the Sun. Could we see the shadows cast by the moons upon the cloud tops of Jupiter? Again, software can simulate the view accurately. The answer is yes. Earthlings with powerful amateur telescopes are capable of seeing the shadows.

Play the video and watch for several things in this simulation. The first is Callisto casting its shadow on Jupiter. Over the course of several hours, it moves across the entire face of the planet. Next, Ganymede and Europa approach from the left. At 24 sec in the video, both of their shadows are cast. Also, Callisto’s shadow moves off the planet and the moon Io disappears into the shadow of Jupiter just off the right limb of the planet.

Watch at the 30 sec time how Europa is occulted by Ganymede. Both shadows are still visible but they become one briefly at the 32 sec mark. Finally, at 38 sec, both moons and their shadows are off to the right. Did you notice how Io emerged to the left of Jupiter in the distance? You might need to view both of these videos a few times.

On 15 August 2021, the moons were actually positioned as in my simulation above for viewers in the western Pacific region. Christopher Go of Cebu City, Philippines, captured images that night. He was fortunate to enjoy clear sky conditions for the duration of these events. His images are posted on his site. Scroll down his page until you reach August 15, 2021. The Astronomy Picture of the Day APOD highlighted his work.