Sunstanding

If you were to look at the Sun (but don’t!) this afternoon, you would be seeing it against a remote background of stars on the border of Taurus and Gemini.

In this chart, the Sun is shown, exaggerated 5 times in apparent size, at the date of the solstice, June 20 20:50 Universal Time (which is 5 or more hours earlier by clocks in North America. Also it is shown at the beginnings of months, at 3 times its size; and every day, at actual size. See the end note about enlarging illustrations.

Stars, other than the Sun, are sized in proportion to their astronomical magnitude (brightness) and colored to indicate their spectral types. More dim and distant stars are shown within 5° of the Sun. Planets that happen to be near the Sun are shown with different symbols, though also sized for magnitude like the stars.

You wouldn’t really see those stars, unless the Sun happened to be eclipsed. We know that they are there, and that the Sun is at that positon among them, by deduction from observations at other times. What you are seeing, and perhaps feeling on your skin, is that the Sun has reached the top of a celestial arch: its path, the ecliptic.

We could call that point the “keystone” of the arch, though that nickname is already in use for something else, a square of stars in the constellation Hercules.

From its highest northern point, the Sun beams down most steeply on us in our planet’s northern hemisphere.

There is more clarification on the cause and effects of the solstice in our page about “Seasons.”

Another pleasing effect has been discovered by scientists. Beech trees, in forests far apart over the northern hemisphere, use it to time the beginning of their seed production. They must have evolved a mechanism that is triggered by the longest daylight, even though the length of daytime is changing most slowly near the solstice.

Another “behavior” of the beech forests is that in some years they produce their seeds abundantly, ensuring that the animals who disperse them don’t eat all of them, in other years sparsely so that vegetative energy is restored. This has obvious benefit. The newspaper report on the research implies that there is a functional relation between the varying-abundance and the timing-by-solstice, but does not, to me, make that clear; perhaps it is in the original article.

Language curiosities and delights department

Beech: to that tree we owe the word book, because its wood or bark was once used as writing material.

What about solstice, Latin solstitium, “Sun-standing-place”? It’s a twig on a huge tree of “remaining in place” words from a root sta- in Proto-Indo-European, the language ancestral to ours. Some came through the Germanic branch, but more of them through the Latin verb whose “principal parts” are sto, stare, steti, statum.

Stand understand stay stead steady instead homestead state station status statistic estate statue  stable constable stalwart constitute substitute solstice interstice.

Others are more dubiously from the same root: stall install steel.

Or are from a root stel- that may or may not be related: step stallion stout stalk stale stalactite stele.

Or are from a curiously not-quite-the-same root in the proto-language: sed-, “remaining in place” but on the basis of a different part of the body: sit sedate session, and, more surprisingly, nest.

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

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.

Sometimes I make improvements or corrections to a post after publishing it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version. Or, if you click ‘Refresh’ or press function key 5, you’ll see the latest version.