Skywatch for the week of May 8, 2023
Mon May 8, 2023 THE MOON AND THE HORSESHOE CRAB
In the springtime, usually in the month of May when the moon is new or full, and the Atlantic Ocean tide is high, horseshoe crabs mate and lay their eggs in the sand at the water's edge. Not a true crab at all, but a distant relative of spiders and scorpions, the horseshoe crab is often called a living fossil because its kind has existed unchanged for hundreds of millions of years. Far above, the moon shines down upon them from a distance of a quarter of a million miles. Horseshoe crabs can hardly see the moon, lacking proper eyesight for the task, but they are nevertheless driven to perform their mating ritual according to a very ancient tradition, following the rhythm of the lunar spring tides of May.
Tue May 9, 2023 ANNIE CANNON’S OBAFGKM
On May 9th, 1922, astronomers adopted Annie Jump Cannon’s stellar classification system. Annie Cannon worked at the Harvard Observatory, where she sorted and catalogued stars by their spectra. When you look at the light of a star through a specialized prism, a spectroscope, you can see that there are thin gaps where the colors are missing. The spacing of these gaps can be matched up with those of heated gases in the lab, telling us what elements are present in those stars – kind of a cosmic bar code. Cannon sorted the stars, and after some adjustments, it resulted in a ranking of stars from hot to cool: O, B, A, F, G, K and M, which countless astronomy students have memorized by using this simple phrase – “Oh, Be A Fine Girl (or Guy,) Kiss Me!
Wed May 10, 2023 CECILIA PAYNE GAPOSCHKIN
Cecilia Payne Gaposchkin was born on May 10, 1900. At the age of 25, she decoded the light from stars, revealing their chemical compositions. When a spectroscope, a device that like a prism, splits starlight into a rainbow of colors, we find dark gaps in those colors, places where the outer atmosphere of a star has absorbed those wavelengths of light. These absorption lines are like cosmic fingerprints, telling us what elements are present in a star. Cecelia Payne was able to prove that hydrogen and helium are the most abundant elements, the rest of the periodic table making up only 2 percent of a star’s mass. Cecilia also said, “Your reward will be the widening of the horizon as you climb. And if you achieve that reward you will ask no other.”
Thu May 11, 2023 GENERAL RELATIVITY DAY
On May 11th, 1916, Albert Einstein's General Theory of Relativity was announced. It supplemented his earlier work on "special relativity", which stated that light travels at the same speed, whether you are moving toward the source of the light, or away from it. With general relativity, Einstein suggested that space itself is curved, the amount of curvature depending on the gravity fields of massive objects like stars and galaxies. Planets don't follow orbits because the sun is pulling on them; rather, they revolve because the sun's mass makes a big dent in the fabric of space-time, and the planets travel like marbles rolling on the inside of a funnel. Our sun’s gravity field is so great that the positions of distant stars are shifted by it. It's all pretty deep.
Fri May 12, 2023 PLANETARIUM SHOW: FORWARD TO THE MOON
In 1972, the last two people to walk on the moon returned to earth. Since then, nobody has gone to the moon, our nearest neighbor in space. Now many people don’t believe we’ve ever been to the moon, that it was all some elaborate hoax. But Jack Schmitt is still alive, and like him, I have also examined moon rocks, and discovered that these rocks are not from earth. In our new planetarium show, “Forward to the Moon,” A recording of Dr. Schmitt talks about his mission and prepares us for our return through NASA’s Artemis program. Shows will be at Indian River State College’s Hallstrom Planetarium this Friday – that’s tonight - at 7 and 8:30 pm, and on Saturday at 1 and 2:30 pm. You can get tickets at the IRSC box office - call 772) 462-4750.