Mon Jun 29, 2026 JUNE FULL MOON
The moon is full today. It rises out of the east in the early evening, and can be found in the southern sky at midnight. By dawn the full moon will set in the west. The names for the June full moon are many: according to the Ponca Indians, this is the Hot Weather begins Moon – no argument there. Back in Europe, this was the Rose Moon, so named for the pink color of this full moon, which rides low in the southern sky. The Omaha Indians call this the Moon When Buffalo Bulls Hunt the Cows; to the Tewa Pueblo it’s the Moon When the Leaves are Dark Green. The Winnebago call this the Corn Tasseling Moon, while the Sioux regard it as the Moon of Making Fat. But to the Objiwe (Chippewa) Indians, this is the Lovers' Moon, named for En-a-ban'dang the dreamer and A-nou-gons', or Little Star, who first met when the full moon rose.
Tue Jun 30, 2026 TUNGUSKA
Back in the year 2013, an early morning fireball lit up the sky over Chelyabinsk, Russia. Shock waves from the impact shattered windows, injuring over a thousand people. Now this wasn’t the first time such a thing had happened. On June 30th, 1908, something much, much bigger blew up in the atmosphere above the Tunguska region in Siberia. Eyewitness reports sound a lot like the Chelyabinsk event. A brilliant blue light, like a second sun, flashed across the early morning sky. It was followed by a sonic shock wave that broke windows, killed wildlife, knocked people to the ground, and shook the earth. The Chelyabinsk impactor was a rock over fifty feet across, which broke apart about ten to 15 miles above the surface. The total energy of the blast was roughly equal to that of dozens of atomic bombs. The Tunguska blast was at least five hundred times more powerful.
Wed Jul 1, 2026 HENRIETTA LEAVITT
On July 6, 1868, the American astronomer Henrietta Leavitt was born. She worked at Harvard Observatory, and while cataloging a class of stars known as Cepheid variables - named for the fourth-brightest star in the constellation Cepheus the King - Leavitt analyzed the light curves of various Cepheids. Variable stars change their brightnesses over time; this is caused by the star’s expanding and contracting as it reaches the end stages of its life. When the star expands, it becomes brighter, when it contracts, it dims a bit. Henrietta Leavitt discovered that there was a relationship: Cepheid variable stars that were intrinsically brighter, or larger, than others, took longer to go from bright to dim to bright again. This made it possible to figure out how far away distant galaxies were, and gave us a much larger measuring stick to determine how far away things are in the universe.
Thu Jul 2, 2026 PRINCIPIA
On July 6 1686, Principia Mathematica was published in England. Principia was Isaac Newton’s great book on gravity and motion, which became a major breakthrough for our understanding of how the Universe works. His three laws of motion – inertia; force equals mass times acceleration; and action-reaction, plus the relationship between gravity, mass and distance, are still in use today, showing us how we can send rockets to the moon and beyond. Edmond Halley paid for Principia’s publishing, because he wanted it to help him work out comet orbits. Halley asked the Royal Society to pay for it, but they’d tied up all their money in a beautiful book, the “History of Fishes”, which nobody bought. Years later, when Halley wanted payment for his duties as secretary, they just gave him a lot of the fish books and suggested he could sell them and make some money that way.
Fri Jul 3, 2026 4TH OF JULY COSMIC FIREWORKS
On the 4th of July in the year AD 1054, a bright star appeared in the eastern predawn sky. It was near the star Al Hecka, the forward horn tip of the constellation Taurus the Bull. For the next month this new star, this “nova,” was so bright that it could even be seen in the daytime! As summer drew to a close, the star faded out of sight and was seen no more. In Europe there is no written record of this star’s appearance: either no one was looking up then, or more likely, the skies were overcast throughout its appearance. But Chinese astronomers made note of this “guest star,” as they called it, and that’s how we know about it today. If you’re out before sunrise this month, aim your telescope at that part of space behind the forward horn tip of Taurus, and you’ll find the Crab nebula, the exploded remains of a supernova - cosmic fireworks from nearly a thousand years ago.