Skywatch Line for Monday and Tuesday, June 17th and 18th, 2019

This is the Skywatch Line for Monday and Tuesday, June 17th and 18th, written by Joe Slomka

The Sun sets at 8:36 PM; night falls at 10:53. Dawn begins at 2:59 AM and ends with the Sun rising at 5:16.

The sky, at Civil Dusk, hosts 3 bright planets. In the West, Mars and Mercury jointly inhabit Gemini. Mars appears 98% illuminated, 3 arc-seconds in size and shines with 1st magnitude. However, it is only 10º high. Mercury lies a half degree from Mars, is 50% lit, shines with zero magnitude and is twice Mars’ apparent size. This is Mercury’s closest approach to Mars, and a rare chance to see 2 planets in the same binocular view. Both set at 10:19 PM.

Eastern Jupiter rises in Ophiuchus at 7:48 PM. It sparkles with minus 2nd magnitude and is 46 arc-seconds in size. By Nightfall, it is 21º high and is best observed at 12:25 AM. Telescopic observers can see Jupiter’s Great Red Spot at 10:05 PM on Monday and at 3:52 AM on Wednesday, but both events happen when the planet is quite low. Beginning at 12:06 AM on Wednesday, they can see the moon Io and its shadow crossing across the giant planet’s face; Io’s trip ends at 2:30 AM.

Dwarf planet 1Ceres rises in Scorpius at 11:25 PM, shines with 7th magnitude and is 27º high. The tiny asteroid lies about 2º from the star Graffias and sets at 4:14 AM. Finder charts are available from various astronomy websites.

Monday’s Full “Trees Fully Leafed” Moon rises, in Sagittarius, at 9 PM, blazing with 12th magnitude and 14º high. It is best observed at 1:41 AM and sets at 6:21 AM. Tuesday sees a thinner and slightly dimmer Moon rising at 9:53 PM, being best observed at 2:33 AM and setting after Sunrise.

Saturn rises in Sagittarius at 9:55 PM, shines with zero magnitude and about 18 arc-seconds in size. It is best observed at 2:31 AM and also sets after Sunrise. Tuesday’s Moon parks itself only 1º from Saturn all night, ruining views of its rings.

Neptune, in Aquarius, rises at 12:48 AM, glows with 7th magnitude and is 22º high at Dawn. Uranus, in Aries, rises at 2:31 AM, glistens with 5th magnitude. Early bird observers should begin as soon as possible due to the brightening sky.

Several dim but lovely constellations are sandwiched between brighter Pegasus, Aquarius and Cygnus. One of these is Delphinus, the Dolphin. It looks like a diamond with a tail and replicates a dolphin leaping out of the water. It is found midway between Pegasus’ and Cygnus’ noses.

There are two Greek myths about Delphinus. One states that Arion, a rich poet, was threatened by covetous crewmen while he was traveling. When he was flung into the sea, he was rescued by a dolphin, which carried the poet to the Greek coast.

Most star names are derived from legends or description. Delphinus is an exception. Its two brightest stars, Alpha and Beta, were the subjects of a practical joke. An Italian astronomer, Niccolo Cacciatore, decided to give them proper names. In Latin, his name was “Nicolaus Venator”. He assigned the names “Sualocin” to Alpha, and “Rotanev” to Beta. These names are “Nicolaus Venator” spelled backwards. The practical joke stuck! Today, these are accepted official names for Alpha and Beta Delphini.

Star names are a combination of various languages: Greek, Latin, Arabic, and invented as the example just mentioned. The Albany Area Amateur astronomers have their monthly meeting at miSci at 7:30 PM, Thursday. Club member Sam Salem will talk about stars with Arabic names. All club events are free and the public is welcome.

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