Skywatch Line for Friday, October 2, through Sunday, October 4

This is Dudley Observatory’s Skywatch Line for Friday, October 2, through Sunday, October 4, written by Alan French.

The Moon reaches last quarter on Sunday afternoon, so a waning gibbous Moon rises late in the evening on Friday and Saturday, and it will be a waning crescent when it rises Sunday night. The Moon rises at 10:10 pm Friday, 11:02 pm Saturday, and 11:57 pm Sunday.

In the early evening the Milky Way, that hazy band that is the combined light of many distant stars in the plane of our galaxy, stretches high across the sky. It may be invisible to people in or near the city, where the lights brighten the sky, but it is a lovely sight from the dark skies away from town. Around 8 pm it stretches roughly from the south southwest to the north northeast. It is brightest and broadest in the south, a beautiful sight as it passes overhead through Cygnus, the Swan, and its luster diminishes as it reaches the distinctive “W” star pattern of Cassiopeia, the Queen, high toward the northeast.

Dark skies are not the only requirement for your best views of the Milky Way – your eyes should also be thoroughly adapted to the dark. You’ve certainly noticed that your eyes gradually get used to the dark, allowing you to see better with time. There are two changes. The pupil opens wider within seconds, allowing more light into the eye. There is also a chemical change which greatly increases your eye’s sensitivity. The full transformation takes 30 to 40 minutes.

White light ruins your dark adaptation and the process has to start again. To preserve their night vision amateur astronomers use dim red lights, which allow reading star charts and notes without ruining one’s night vision. Red plastic or construction paper can easily turn a regular flashlight into an astronomer’s flashlight – but remember it should be just bright enough to read charts when you are completely used to the dark.

A reclining lawn chair is ideal for exploring the Milky Way, and there is even more to see with binoculars.

We often recommend observing the Moon with binoculars or a telescope when it is near first quarter. It is a similarly great target near last quarter – but the timing is not convenient for most people. If you’re an early riser the Moon, just past last quarter, will be high in the southern sky at 6:00 am Monday morning. When the Moon is high in the sky the views tend to be steadier and detail better seen. Monday morning the sunset line or terminator is near the center of the Moon’s disk, ideally placed for viewing. Along the terminator shadows are long and details stands out in bold relief.

If you took advantage of National Observe the Moon Night last Saturday, just before first quarter, you probably noticed the Moon was not very high in the sky then.

Skywatch Line for Monday and Tuesday, September 28th and 29th

This is the Dudley Observatory Skywatch Line for Monday and Tuesday, September 28th and 29th written by Joe Slomka.

The Sun sets at 6:42 PM; night falls at 8:16. Dawn beaks at 5:15 AM and ends with sunrise at 6:50.

The darkening sky reveals only one bright planet – Saturn. Saturn appears moderately low in the southwestern sky. It appears between Libra and the head of Scorpius and is slowly closing in on the Scorpion. Saturn sets at 9:21 PM.

Nightfall reveals Neptune still keeping station in Aquarius. Finder charts, found in astronomy magazines, websites and apps, assist in locating this distant world. Neptune sets at 4:30 AM.

Normally visible Uranus, in Pisces, may not be observable on Monday and Tuesday evenings. The Moon, which experienced an eclipse last night, has parked itself less than two degrees from Uranus. The overwhelming lunar brilliance will probably drown Uranus by its light and make observation of the planet difficult. The sixteen-day-old Moon rose after 7 PM on both nights and sets during daylight, appearing nearly full on both evenings.

Astronomical Dawn introduces three new characters on stage, in Leo. Brilliant Venus rose at 3:18 AM, second in brightness only to the Moon. In high-powered binoculars or telescopes, Venus appears about one-third illuminated and keeps shrinking in size. First magnitude Mars is next to rise, at 3:57 AM; it lies about eleven degrees from Venus, but only three degrees from Leo’s brightest star, Regulus. Its rusty color distinguishes it from the white star Regulus. Jupiter is the last to rise, at 4:38 AM. It is quite low on the eastern horizon, about seven-an-a-half degrees to Mars’s lower left. All three remain up well into daytime and, in the coming months, will populate the pre-sunrise sky.

Since Autumn began last week, let us consider the Fall constellations. Some “Summer Constellations” are misnamed. They rise in early summer, but are best seen in late summer or early fall. Between nightfall and midnight, the Andromeda saga is displayed. Her parents are Cepheus and Cassiopeia. Cepheus is house-shaped and points to the North Star. Cassiopeia looks like a “W” or “M”. Andromeda is depicted by a chain of stars that flow from the upper left of the Great Square of Pegasus, the horse. Perseus is a constellation below Cassiopeia with a long and a short leg. Cetus, the sea monster, swims low on the horizon. These constellations together account for twelve percent of the celestial sphere. Also visible are Lacerta, the lizard and Triangulum, the Triangle. All are in excellent position to be seen tonight.

Skywatch Line for Monday and Tuesday, September 21st and 22nd

This is the Dudley Observatory Skywatch Line for Monday and Tuesday, September 21st and 22nd written by Joe Slomka.

The Sun sets at 6:55 PM; night falls at 8:30. Dawn breaks at 5:07 AM and ends with the Sun rising at 6:42.

The Moon officially turned First Quarter early Monday morning, but rose in our skies in the afternoon. The eight-day-old Moon is already quite bright, at magnitude minus 10.1 and inhabits Sagittarius both nights. It appears a bit more than half illuminated and sets after midnight.

Saturn is the only other brilliant object in our sky. Saturn still resides in Libra and appears midway between Libra and the head of Scorpius. By nightfall, it is only ten-and-a-half degrees high and sets about 9:30 PM.

Twilight’s end reveals the distant planets Neptune and Uranus. Neptune is nearly eighth magnitude in Aquarius, and Uranus is a brighter 5.7 in Pisces. Both require charts, which are found in astronomy magazines, websites and apps. Neptune is best observed at 11:30 PM, and Uranus at 2:04 AM. Neptune sets at 5 AM, while Uranus remains up past sunrise.

By 10 PM, Perseus is moderately up in the eastern sky. At 11:30 PM on Tuesday, the star Algol (also known as Beta Persei) dims. Algol, the “Demon Star,” varies its light every 2 days, 20 hours and 49 minutes. It fades from second magnitude to third – easily seen by the naked eye. The entire cycle takes about nine hours. John Goodricke theorized that a dimmer star was partially eclipsing a brighter star. In 1889, the new technique of spectroscopy verified this theory. The main star is one hundred times the Sun’s luminosity. The eclipsing star is actually slightly brighter than our Sun. There is a third star that orbits the system once every 1.8 years, but plays little part in the occultation. The system is about 96 light years away and the most easily studied “eclipsing binary.” Astronomy magazines and websites provide timetables of its eclipses. Begin observing about 10 PM.

Astronomical Dawn sees the arrival of three bright planets. Venus rises first, at 3:27 AM. It blazes in the dim constellation Cancer. Under magnification, it appears about a third illuminated. Mars emerges a half hour later and is about eleven degrees to Venus’ lower left. Mars lies about one-and-a-half degrees from Leo’s brightest star, Regulus. Jupiter brings up the rear, rising before 5 AM. All three are great observing targets and all will remain in our skies for the rest of the year. They also experience several close conjunctions later this month.

The Vernal Equinox takes place at 4:21 AM Wednesday. This happens when the Sun dives below the projection of Earth’s equator on to the sky. The Sun also rises exactly East and sets exactly West. The word “equinox” means, “equal night.” Indeed, day lasts 12 hours and night also lasts 12 hours. This event signals the beginning of Fall for the Northern Hemisphere and Spring for those in the Southern Hemisphere.