On the morning of Tuesday May 12 comes this concentration of three bright bodies within a circle less than 5 degrees wide.
See the end note about enlarging illustrations.
Jupiter has been catching up wit Saturn, and now when the Moon pays its monthly visit they are close enough to form this trio. It is at its tightest on May 12 at 14h Universal Time, which is 4 or more hours earlier by American clocks, so the nearest time for viewing the trio is the morning hours of May 12.
The centers of the three fit within a circle of diameter 4.7°. This is as seen from the center of the Earth; from our northern latitudes the Moon, which descended through the ecliptic on May 10, will appear farther south, so that the gathering appears less tight. In the picture, the Moon is drawn – at twice its real size – in the positions where it is seen from the location, but the arrows between Moon dates are where the Moon would be seen from Earth’s center.
This space view is from 15° north of the ecliptic plane, and shows the paths of Earth, Jupiter, and Saturn in May 2020, with sightlines from Earth to those planets at May 12 14h UT. The dashed line indicates the vernal equinox direction.
After this trio event, the Moon will reach its Last Quarter positon on May 14 (14 UT), near the spot marked “Earth’s direction of travel.” The Last Quarter Moon, 90° west of the Sun, is crossing our orbit ahead of us.
And, because Earth is starting to overtake the two planets on the inside, both go into apparent retrograde motion, Saturn on May 11, Jupiter on May 14. One result is that there comes a quasi-conjunction, a moment when the angular distance between them is at a minimum before opening back out: this will be on May 18, when Jupiter will be 4.7° west of Saturn.
To add to the complexity, little Pluto appears close by but in the farther background.
Quite a geometric tangle. To clarify it to myself, I had to trace the to-and-fro movements of Jupiter and Saturn from month to month down my Zodiac Wavy Chart for 2020,
The two giants will continue to retrograde, through their oppositions on July 14 (Jupiter) and 20 (Saturn); will resume forward motion on Sep. 12 (Jupiter) and 29 (Saturn). Their 20-year conjunction will come on November 2 as seen from the Sun, and on December 21 as seen from Earth.
By the way, we have walked to the King’s Observatory, but I’ll set that in perspective later.
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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”, 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.
Sometimes I make improvements or corrections to a post after positing it. If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.
This weblog maintains its right to be about astronomy or anything under the sun.
I and many others will benefit from your practical and encouraging words … thanks! Despite the fact that I am fond of astrology from https://horo.io/, I constantly remind myself that the planets continue their cycles, and that we all, I hope, will develop thanks to this experience. Stay fit.
Woke up just in time to see the trio. Then on my drive to work, I was stopped at a red light and I looked at the moon and could see Jupiter above it, even though the sun was up. That makes the 3rd time I’ve seen Jupiter during the day. I made a point to see Jupiter last year before sunset. I also saw it a couple weeks ago shortly after sunrise while stopped at the same red light and watching a jet that happened to pass right below it.
I am glad to have found your blog. Thanks for these posts. Maybe it’s time for an pre-dawn walk.
Thanks very much, Guy. I appreciate being able to see the effect of latitude on the Moon’s parallax. In celestial navigation the Sun, planets, and stars can all be assumed to be infinitely far from the Earth, so there’s no need to account for parallax based on the observer’s location on the surface of the Earth. But the Moon is close enough to appear in a different place in the sky depending on how far north or south you are, and how far east or west you are relative to where the Moon is rising, transiting the meridian, or setting. Add in the fact that the Moon is moving relative to the background stars by about half a degree (give or take) every hour, and the math gets very complicated. But, exactly because the Moon is moving relative to the background stars, you can use the Moon’s angular distance from a star or planet to calculate Greenwich Mean Time (basically UTC), which you need to know in order to find your longitude. But the calculations take so long that you only know what the time was when you started the calculations, and now it’s two hours later, and you have less hair!
On a much longer time scale, I’m imagining our ancestors watching the most distant known planets, Jupiter and Saturn, doing a stately pavane in the sky. If your culture understood the 20 year cycle, and you were fortunate enough to live your allotted three score and ten, you would know that you were seeing something that would only happen three times during your lifetime. It’s not a far leap to imagine people giving a great significance to this cycle.
This is the large subject of Great Conjunctions. It occurs to me that what is needed is a graph of longitudes (like those I used to do for Uranus and Neptune) showing the lines for Jupiter and Saturn intertwining. When their conjunction is near opposition, the lines would cross three times. Remind me to do it WTA, When Time Allows!
That was a new word for me. A stately dance from the 16th century.
Root word of pavane means peacock
Well done going to the king’s observatory! tempted to visit myself when next down that way mind will golf have resumed by then?I spotted Jupiter a few nights back,or rather mornings,at an ungodly 0407.i looked out the window and saw a bright object over the Yorkshire Moors and a quick look with my Zeiss miniquick 5×10 monocular proved it to be Jupiter and 1 Moon visible too.