Mon May 18, 2026 THE SUN AND THE SOLAR YEAR
Over the course of a year, the sun drifts eastward against the background of stars. It’s a very slow motion caused not by earth’s rotation, but by its revolution about the sun, which displaces the sun’s position by about 1 degree of angle a day – that’s less than the width of your little finger at arm’s length! After roughly 365 days, the sun returns to where it had been exactly a year ago. Right now the sun appears below the Pleiades star cluster in the constellation Taurus. Next month it will be in Gemini, the month after that in Cancer, then Leo, and so on until next May 18th, when it will be alongside the Pleiades again. This defines the solar year as the amount of time needed for the sun to go full circle, once around the zodiac in the heavens.
Tue May 19, 2026 FRANKLIN EXPEDITION
Today’s Skywatch was written by my student assistant, Isabella Gargiulo. Here she is. On May 19th, 1845, Sir John Franklin and his two ships, the HMS Erebus and HMS Terror, departed on their ill-fated expedition from England. Their goal was to find something that didn’t exist - the fabled Northwest Passage, an alternate trade route connecting Europe and Asia. As they got closer to Earth’s powerful magnetic north pole, their compasses became unreliable and failed. The crew resorted to dead reckoning and celestial navigation, including the use of sextants - an instrument that measures angular positions of the sun, the moon and the bright stars – and chronometers, precise clocks to accurately mark the time to figure out where they were. But the sky was obscured and intense arctic cold caused all of their instruments to fail; everyone in the expedition perished.
Wed May 20, 2026 PLACES IN THE SKY: MAY
Can you identify the thirtieth largest constellation in the sky? It is bordered on the north by Auriga and Lynx the Bobcat; on the east by Cancer the Crab; on the south by Canis Minor and Monoceros the Unicorn; and on the west by Orion the Hunter and Taurus the Bull. This constellation’s brightest stars seem to trace out a long rectangle in the heavens, which in the Middle East were seen as a stack of bricks. But in Italy, they represented Romulus and Remus, the founders of Rome. The Greeks named them Castor and Pollux, which are also the names of this constellation’s two brightest stars, and tonight the waxing crescent moon and the planet Jupiter are beneath Pollux, while the brilliant planet Venus can be found just to the east, near the feet of Castor. Can you name this star pattern, the third constellation of the zodiac? It is of course, the Gemini, visible in the southern sky after sunset.
Thu May 21, 2026 THE BIG DIPPER, THE GREAT BEAR
The Big Dipper is in the northern sky after sunset tonight. It’s made up of seven fairly bright stars which trace out the pattern of an old pot. Three stars - Alkaid, Mizar and Alioth - mark its handle, and four stars – Megrez, Phecda, Merak and Dhube, form the pot.Now the official constellation in this part of the sky is Ursa Major, the Great Bear, in Greek mythology a maid who was transformed into a bear and carried into the sky by Zeus, the king of the gods. The Big Dipper makes up the bear’s back and the tail. There are fainter stars in front of the Dipper’s bowl and beneath it which faintly trace the outline of this bear, but the Dipper is a whole lot easier to see. Just to make it a challenge, though, the Big Dipper is now placed upside down, so that the open end of the pot would spill out its contents onto the floor of the sky.Maybe that's where the Milky Way comes from...
Fri May 22, 2026 ARTHUR CONAN DOYLE
Arthur Conan Doyle, born on May 22nd, 1859, invented the fictional detective Sherlock Holmes, one of my favorites. But Holmes confessed to Doctor Watson that he didn’t know that the earth orbited the sun: “What… is it to me? You say we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or my work.” But I think that astronomy would appeal to his powers of observation. And through inductive reasoning, Holmes could infer that if we live on a planet, one of many, that goes round the sun, then it would be logical to assume that there were other planets out there, going ‘round other suns. And he did say, “When you have excluded the impossible, whatever remains, however improbable, must be the truth.” Sounds a lot like black holes to me!