Swimming up sky and up river

Little Mercury, elusive in the Sun’s glare, is becoming more and more findable in the dusk, as it climbs toward its easternmost elongation – angular distance from the Sun – of May 17.  That will be its highest evening appearance of the year, for our northern hemisphere.

See the end note about enlarging illustrations.

The arrows through Mercury, the Sun, Venus, and Mars show their movements, against the starry background, over a span of five days.  You can see that Mercury is eastering faster than the Sun; it will slow toward May 17.

In January we summarized Mercury’s three morning and three-and-a-half evening appearances of the year.

This graph compares them – gray for the evening and blue for the morning excursions.  The top figures are the maximum elongations, reached at the top dates shown beneath.  Curves show the altitude of the planet above the horizon at sunrise or sunset, for latitude 40° north (thick line) and 35° south (thin), with maxima reached at the parenthesized dates below (40° north bold).

Blue Planet Department

Yesterday evening, a small planêtês or wanderer – a young minke whale, about four yards long – reached an extreme elongation from the sea.  That is, se (my pronoun, which I’d rather use than “he or she” pr “it”) swam up the Thames to the farthest point possible: the Richmond lock, which partially stops the tidal river.

At the side of the lock is a line of rollers on which boats can be pulled past.  The tide must have been slightly over them, and the whale tried to get through, and became stuck.

This was about 7 PM.  A team from the London fire brigade and the Royal National Lifeboat Institute managed to get hem off the rollers by 1 AM.  Se was towed downriver, but at Isleworth – where we live – se broke free, swam away, and disappeared.  Latest we know is that the public is asked to report any sighting of the whale, which is not in good health.

Tilly learned about the event this morning, and I got the impression that the whale was at the Richmond lock, and rode along there.

The lock is under the footbridge.  Photographers were still there but no whale.

In our sky scene, Cetus, the constellation of the Whale, is below the horizon, just to the left of where the Sun is.  Let’s hope Richmond Lock Minke will soon be back down in hes native sea.

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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 publishing  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.