Fickle planet

Mercury reaches today its farthest out from the Sun into the evening sky.

See the end note about enlarging illustrations.

The arrows through the moving bodies – Mercury and the Sun – indicate their motion over 5 days (in relation to the starry background). From now on, Mercury’s motion is a little slower than the Sun’s. It will fall back between us and the Sun on Sep. 23.

Mercury is shining at magnitude 0.3, like some of the brightest stars, but, unfortunately for us on Earth’s northern hemisphere, it happens to be well south of the ecliptic. So it is, at the time and place of our picture, only about a degree above the horizon. As shown in this comparative graph of Mercury elongation maxima, from page 104 of our Astronomical Calendar 2022,

the August elongation maxim is greatest for the whole year (the top figure, 27.3°), yet is for latitude 40° north the lowest above the setting Sun (thick black curve), whereas for a south-hemisphere latitude is the year’s highest (thin black curve).

If our scene were instead drawn Australasia or South Africa, the ecliptic and equator would tilt the other way, and Mercury would be at least 15° above the horizon.

The Moon was new (passing the Sun) a few hours earlier today. The figures beside its crescent shape are its “age” – the number of hours past the new Moon moment. Thus if you managed to glimpse it at this time tomorrow (from this location) it would be only 41 hours old – exquisitely slender, yet it has been seen when only 15 hours old.

The Moon’s crescent will be slightly less thin when it appears next evening to the east of Mercury. On Aug. 31 it will be about 4° above Spica, the “lucida” or brightest star of Virgo.

 

Home Planet Department

Our front door is now painted in the colors of Ukraine’s flag.

Not really. Peter, our Polish painter, has prepped the door for repainting by touching some spots with wood filler.

But we do need to keep the Ukrainian flag flying; to hold our governments to their support for the bombarded country. They are distracted by several other crises; yet all those crises are compounded by, some caused by, the corrupt superpower’s invasion of its neighbor.

 

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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image” or “Open image in new tab”, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

This weblog maintains its right to be about astronomy or anything under the sun.

 

3 thoughts on “Fickle planet”

  1. It clouded over here but Mercury was probably too low anyhow.As far as I can recall Mercury and Neptune are the only planets I’ve not seen in 2022.I was going to look for Neptune during my Bortle 2 camping trip in the Galloway Forest Dark Skies Park in Scotland but insects kept biting me and it was too hard to focus on the only none naked eye planet.I just made Uranus out naked eye there.

  2. Guy, thanks so much for your many excellent contributions to the world of amateur astronomy. There is nobody else “out there” like you and your visuals.

  3. There was a great view of Mercury in the western sky earlier this evening (Saturday) in Sydney.

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