Mon Jul 6, 2026 EARTH AT APHELION
Today at 1:30 pm Eastern Daylight Time, the planet Earth will be a little over 94 and a half million miles from the sun, a point in its orbit known as aphelion. The earth’s orbit is slightly elliptical, so sometimes we’re a little closer to the sun than at other times. That near point is called perihelion, and the far point is known as aphelion - that’s where we are right now. So how come we're having summer? Well, it’s summer now where we are, but winter has just begun for folks south of the equator. Temperature changes occur because our planet is tilted over a little, about 23 and a half degrees, from straight up and down. Right now, our hemisphere is leaning inward, which puts the sun higher in our sky, and causes summer; in the winter the top half of earth leans away from the sun, putting it lower in our sky, which cools things down.
Tue Jul 7, 2026 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.”
Wed Jul 8, 2026 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 – 250 years ago today. 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.
Thu Jul 9, 2026 MIZAR AND ALCOR
Today’s Skywatch was written by Hallstrom planetarium assistant Vela De la Mare. Have you ever seen the big dipper? You can find it tonight just after sunset, setting in the western sky. When we usually describe this star pattern, we’ll say it has 7 stars: 3 in the handle, and 4 in the bowl. However, there’s an 8th star, hiding nearby, visible on a really clear night – or with the help of some magnification. This star is named Alcor, and it’s hanging out right next to the brighter star Mizar in the center of the handle. These two stars are so close together, that they often appear as just one to us on Earth. If we travelled 83 light years to go see them, we’d find that Alcor is itself a double star, and Mizar has a whopping 4 stars in its system. 6 stars – all hiding behind one shining dot in the Big Dipper.
Fri Jul 10, 2026 FAREWELL SKYLAB
Forty-five years ago, 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.
