Skywatch Line for Friday, July 26, through Sunday, July 28, written by Sam Salem
This is Dudley Observatory’s Skywatch Line for Friday, July 26, through Sunday, July 28, written by Sam Salem.
On Friday, Sun rises at 5:41am and sets at 8:22pm; Moon sets at 11:53am and rises at 11:18pm.
The last quarter Moon will fall on Saturday. It’ll rise after midnight and will set around noon. Look for it high in the sky before dawn.
Mercury and Venus are deep in the afterglow of sunset. Fainter Regulus is down there with them, passing Mercury. Use binoculars or a telescope’s lowest power to scan for them just above the west-northwest horizon starting about 20 minutes after sunset.
Venus is the lowest, but it may be the first you pick up because it’s by far the brightest, magnitude –3.9.
Mars and Jupiter, at magnitudes +0.9 and –2.1, respectively, in the constellation of Taurus, rise around 2 am. Mars shines upper right of bright Jupiter. Their separation shrinks to 9°this weekend. The Pleiades sit above Mars, and Aldebaran is below the two planets. This pattern moves much higher in the east by dawn.
Saturn, at magnitude +1.0, near the Aquarius-Pisces border, rises in the east soon after the end of twilight. Watch for it to come up lower right of the Great Square of Pegasus, which is balancing on one corner. The Square’s top-right edge points diagonally down almost at Saturn, two fists at arm’s length away. Saturn is at its highest in the south, in the steadiest atmospheric seeing for a telescope, just before the first light of dawn. The seeing often steadies down as dawn advances.
Uranus, at magnitude 5.8, at the Aries-Taurus border, is several degrees to the upper right of Mars in the morning sky. You’ll need a finder chart to identify it among surrounding stars.
Neptune, at magnitude 7.9, in the constellation of Pisces, is 11° east of Saturn before dawn begins. You’ll need a finder chart.
On July 28 1851, a total solar eclipse was first captured on a daguerreotype photograph by Busch and Berkowski, at the Royal Observatory in Königsberg, Prussia, now Kalinigrad in Russia. It showed a slight but distinct impression of the corona during the total eclipse. Berkowski, a local daguerrotypist whose first name was never published, observed at the Royal Observatory. A small 6-cm refracting telescope was attached to a 15.8-cm Fraunhofer heliometer and a 84-second exposure was taken shortly after the beginning of totality. Daguerreotype is a photograph taken by an early photographic process employing an iodine-sensitized silvered plate and mercury vapor. A heliometer is an instrument originally designed for measuring the variation of the Sun’s diameter at different seasons of the year.