Mon Apr 20, 2026 NAME THAT CONSTELLATION: APRIL
Can you identify the seventeenth largest constellation? It is bordered on the north by Auriga and Perseus, on the south by Eridanus, on the west by Aries, and on the east by Orion. And this evening the crescent moon shines above its horns, not too far from the Crab Nebula, while the planet Venus appears near the Pleiades star cluster on its shoulders. The red giant Aldebaran is its brightest star. One of the oldest star patterns, in mythology this creature is often seen as a representation of Zeus, who carried the princess Europa across the sea to Crete; or as the seventh labor of Hercules. Can you name this star figure, the second constellation of the zodiac? The answer is Taurus the Bull, now visible in the western evening sky.
Tue Apr 21, 2026 DEATH OF MARK TWAIN
Sam Clemens, better known as Mark Twain, died on April 21st, 1910. Twain was born the same year that Halley’s Comet appeared in the sky. In 1909 he wrote, “I came in with Halley's Comet in 1835. It is coming again next year, and I expect to go out with it. It will be the greatest disappointment of my life if I don't go out with Halley's Comet.” The comet’s orbit brings it close to the sun every seventy-six years on average, but it wasn’t visible to most folks until a week or so after his death in 1910. But there was a brighter comet in 1910, which could be seen in the daytime, in the months just before he died. Perhaps he was thinking of this comet when he wrote, “Death is the starlit strip between the companionship of yesterday and the reunion of tomorrow.”
Wed Apr 22, 2026 STAR POPULATIONS
There are two types of stars in our Milky Way Galaxy –Population I stars like our sun, which are found mainly in the Milky Way’s disk; and Population II stars, which are farther out in the halo, a roughly spherical region that surrounds the galaxy. The orbits of the sun and other Population 1 stars are fairly circular as they revolve about our galaxy’s nuclear bulge. The orbits of the Population 2 stars, on the other hand, weave in and out of the galaxy at right angles to the rest. The bright star Arcturus in the constellation Boötes the Herdsman, which is now rising out of the east at sunset, is a Population 2 star; it’s an intruder, and is passing through the disc, heading southwards.
Thu Apr 23, 2026 WE ARE STARSTUFF
Yesterday I spoke about two different kinds of stars in our Milky Way galaxy. Our sun is a Population I star, and is made of many gases, hydrogen and helium mainly, but also all the other elements, oxygen, carbon, iron and so on. Then there are Population II stars, which contain only hydrogen and helium - the heavier elements are missing. Why? We think the Population II stars are much older, and formed before metals and other heavy elements had been created. In fact, those heavier substances were made inside the oldest stars. When those old stars went supernova, the heavy metals were spilled out into space, where they eventually combined with the debris of other exploded stars to form the next generation of stars like our sun.
Fri Apr 24, 2026 HST 36TH ANNIVERSARY
On April 25th 1990, the Hubble Space Telescope was put into orbit. The shuttle Discovery carried it up and released it 400 miles above the earth’s surface on April 24th, where it began sending back images a month later. After a few bumps in the road caused by a misshaped mirror, the Hubble worked about as well as the biggest telescopes on earth. Corrective optics were put in place a couple of years later, hence it began outperforming all other telescopes. In the past thirty-six years, Hubble has seen ammonia ice storms on Saturn, methane ice on Pluto, nearby red and brown dwarf stars, supernova explosions, globular star clusters in the Andromeda Galaxy, hot matter surrounding galactic black holes, and literally millions upon millions of far-out galaxies and quasars.
