Mon Sep 16, 2024 THE EARTH’S ORIENTATION IN SPACE
If you can imagine extending the Earth’s north and south poles out into space, you’ll find a celestial north pole and a celestial south pole. Extend the Earth’s equator outward, and you can establish a celestial equator in the heavens as well. Polaris, also called the North Star, lies very close to our north celestial pole; but there is no bright South Star to find at the earth’s south celestial pole. As our Earth orbits the sun, the path it follows is not the celestial equator, but another line called the ecliptic, which is inclined 23 and a half degrees to the equator. Now while our planet orbits the sun, the sun in turn orbits the center of our galaxy – but our solar system’s orientation with that path is about 60 degrees over from straight up and down – we’re moving sideways through the Milky Way!
Tue Sep 17, 2024 FULL MOON OF SEPTEMBER. PARTIAL LUNAR ECLIPSE
The moon is full. September’s full moon is the Barley Moon of medieval England, or the Singing Moon in Scotland and Ireland, while in the Americas it is the Corn Moon. The Cherokee call it the Black Butterfly Moon or the Nut Moon. This is also the Harvest Moon, the full moon which occurs nearest the autumnal equinox, the beginning of fall, which will be on September 22nd. Over several nights, the light of this full moon proves helpful to farmers who bring in their harvest of crops after sunset. And just to the west of the moon tonight you’ll find the planet Saturn, appearing as a yellow-tinged star. Later tonight there will be a partial lunar eclipse, which will begin at 10:13 pm Eastern Daylight Time, and will end at 12:47 am – after midnight tonight. This eclipse will be very small, with just a tiny bit of the moon disappearing into the earth’s shadow for a couple of hours.
Wed Sep 18, 2024 PIONEER 11
In September 1979, Pioneer 11 became the first spacecraft to travel past Saturn. Launched in 1973, it took six years to cross the billion-mile gap between Earth and Saturn. When Pioneer 11 passed Jupiter, it nearly got its circuits fried by the giant planet’s powerful magnetosphere. But it made it to Saturn, and Pioneer 11 was first to see Saturn's twisted, outermost F ring. If you’d like to take a look at the ringed planet tonight, you’ll find it in the southeastern sky after sunset, a bright, yellow-tinged star a little bit to the west of the moon in the constellation Aquarius. Small telescopes can reveal those rings, but you can’t see Pioneer 11, even with the most powerful telescopes on earth. The little spacecraft is well to the west of Saturn in the constellation Scutum, over 10 billion miles out, in the great beyond.
Thu Sep 19, 2024 HYPERION
On September 19, 1848, father and son astronomers William and George Bond discovered Saturn’s moon, Hyperion. To them it was just a little point of light that changed position as it orbited the ringed planet. But thanks to the Cassini spacecraft, we see it as another world. Hyperion is over 200 miles in diameter; and ordinarily such a large object should be round, but Hyperion looks pretty beat-up, covered with craters, and very irregular in shape, looking like an old meatball. Its composition is mostly water ice, with some rock and dust added for texture. Hyperion tumbles erratically as it orbits Saturn, probably owing to its irregular shape and the gravitational influence of Saturn’s biggest moon Titan. This evening you can find Saturn in the southern sky in the constellation Aquarius, but Hyperion is a little too small to see without a good telescope.
Fri Sep 20, 2024 FIRST DAY OF AUTUMN
On Sunday September 22, at 8:43 am Eastern Daylight Time, fall will begin. This is the autumnal equinox, a point in time when, if you’re at the earth’s equator, the sun can be seen at the zenith, the top of the sky, at noon. Today, everyone around most of the world enjoys days and nights of pretty much equal length, hence the term “equinox,” which means “equal night”. From now until after the beginning of winter the sun will rise to the south of east and set to the south of west, and its noontime altitude will continue to decrease as well. The 23½ degree tilt of the earth’s axis causes the sun’s path across our sky to drift lower and lower at noon as we move toward winter. But, folks who live below the equator are observing the beginning of spring: the seasons are reversed for earth’s southern hemisphere.
