Mon July 7, 2025 TANABATA DAY: VEGA AND ALTAIR
Today is Tanabata Day in Japan, marking the reunion of the weaver princess and the cowherd. This far-eastern story is over a thousand years old. The Jade Emperor’s daughter, Tanabata or Chih-Nu, loved a herdsman, Niu Lang. The father disapproved, and so he placed them up into the sky; Chih-Nu became the star Vega, and Niu Lang is the star Altair - both stars are well-placed in the eastern sky after sunset tonight. The Emperor then set Tien-Ho, the great Celestial River to separate them. Tien-Ho is the Milky Way, which when the skies are dark, you can see runs between these two stars. But on the seventh day of the seventh month, if skies are clear, magpies gather and with their wings form a living bridge across the Milky Way, so Chi-Nu and Niu Lang can be together once more. Part of a traditional poem recited at this time goes, “the stars twinkle on the gold and silver grains of sand... The stars twinkle, and there they will watch us.”
Tue July 8, 2025 DECLARATION OF INDEPENDENCE
An observatory was built in 1769 in Philadelphia, a couple of hundred feet south of Independence Hall. It was built so that astronomers could observe a transit of the planet Venus that year. Transits occur when either Mercury or Venus passes directly between the earth and the sun; using strong filters, we can safely see those planets as small, dark round dots against the sun’s face. Transits of Venus are rare; they occur in pairs every hundred and twenty years. Seven years after colonial astronomers saw this transit the observatory’s balcony made an excellent platform for the first public reading of the Declaration of Independence, on July 8th,1776. During the Revolutionary War, the Philadelphia observatory housed British troops who occupied the city. And not too many years after the end of the war, the observatory fell into disuse, and sadly, is no longer there.
Wed July 9, 2025 FULL MOON HANGS LOW
All full moons rise at sunset and set at sunrise. So full moons are at their highest around the midnight hour (or 1 am, if you throw in daylight savings time.) But even though it’s at its highest then, July’s full moon isn’t very high. You see, full moons are directly opposite the sun. So they occupy the part of the sky where the sun will be found six months later. Half a year from now it will be winter, and the sun’s path in winter is very low; even at noon it’s not far off the south horizon. In summer the full moon is at the spot where the sun is in winter. So the summer’s full moon mimics the sun’s wintertime path. This also means that full moons in winter can reach the top of the sky at midnight, mimicking the sun’s path in summertime. So this month’s full moon won’t get very far above the horizon, and will be at a convenient altitude for us to admire it, just above the treetops, low in the southern sky at the midnight hour. Check out the full moon these next few nights.
Thu July 10, 2025 JULY FULL MOON
The moon is full tonight and tomorrow. Because thunderstorms are common in July, this full moon is often called the Thunder moon. According to the Sioux Indians, this is the Moon When the Wild Cherries Are Ripe. To the Winnebago, it is the Corn-Ripening Moon, and to the Kiowas, it is the Moon of Deer Horns Dropping Off. To the Omaha Indians, however, this is the Moon When the Buffalo Bellow. In ancient China, this was the Hungry Ghost Moon, named for departed souls who had left no descendants. In medieval times this was the Hay Moon or the Mead Moon, named for the elixir from the meadows of Briton and Europe. After this full moon came the first harvests from the fields and the pagan festival of Lughnasaid, which was later adopted by early Christians and became the celebration of Lammas, or “loaf mass,” in thanksgiving for the first fruits of the farmer’s labor.
Fri July 11, 2025 FAREWELL SKYLAB
On July 11th, 1979 America’s first space station – Skylab - disintegrated when it re-entered earth’s atmosphere, its debris scattered across the south Pacific and Australia. Built from Apollo moon mission hardware, such as the Saturn 5 rocket’s third stage, it was launched in 1973. Over the next year, three different Skylab crews lived in it and made observations of the earth and the sun and the stars. And it provided lessons that would help us stay alive on future long duration missions, such as those aboard the current space station. There was even a racetrack reminiscent of the one seen in the movie “2001: A Space Odyssey”, where astronauts could run laps around Skylab’s inner circumference! One of my duties when I interned at the Hayden Planetarium was to provide daily updates on the anticipated re-entry time of Skylab. It was indeed a sad day when Skylab met its end.
