Category Archives: Skywatch Line

This is the Dudley Observatory Skywatch Line for Wednesday, December 11th, and Thursday, December 12th, written by Louis Suarato.

The nearly full Moon rises at 4:05 p.m., Wednesday. The Moon won’t reach its Full phase and be 100% illuminated until 12 minutes past midnight. If you look low over the southwestern horizon about an hour after sunset, you’ll see Venus and Saturn separated by 2 degrees. Venus will be the much brighter of the two planets, shining at magnitude -3.90 to Saturn’s left. Saturn’s magnitude is 0.58. Saturn sets at 6:30 p.m., followed by Venus a minute later. Venus is currently 86.5% illuminated. Saturn’s rings are currently tilted at 24 degrees. The two planets move apart after Wednesday, with Venus rising higher in the sky, while Saturn approaches the Sun. Mars rises at 4:21 a.m. in Libra. The star less than a degree to the upper right of Mars is Alpha Librae, also known as Zubenelgenubi, meaning “the southern claw”, from a time when Libra was part of Scorpius. Alpha Librae is only .33 degrees north of the ecliptic, so it is occasionally occulted by the Moon and planets. Located about 77 light-years away, Alpha Librae is a double star whose components may be gravitationally bound, but are far apart, and may have an orbital period greater than 200,000 years. Mercury rises at 5:58 a.m., but may be too close to the glow of sunrise to see.

While Venus and Saturn are setting the Moon will be rising above the east-northeastern horizon. The Moon will be at the left foot of the Gemini twin, Castor, and above Orion’s shield. As the sky darkens, you will see that the Moon is near the center of the asterism known as the Winter Hexagon, or Winter Circle. The stars comprising this asterism are Capella, in the constellation Auriga, to the Moon’s upper left; Aldebaran, in Taurus to the Moon’s upper right; Rigel, in Orion to the Moon’s lower right; Procyon, in Canis Minor, almost directly below the Moon; and Pollux, in Gemini to the Moon’s lower left.

This is the Skywatch Line for Monday, and Tuesday, December 9th and 10th, written by Joe Slomka.

The Sun sets at 4:21 PM; night falls at 6:03. Dawn begins at 5:33 AM and ends with the Sun rising at 7:15.

Monday’s 13-day-old Moon rises in Aries at 3:02 PM and sets at 5:21 AM, Tuesday. Tuesday, the Moon, in Taurus, rises at 3:33 PM and sets at 6:27 AM, Wednesday.

Sagittarius houses three of the brightest planets, Jupiter, Saturn and Venus. Minus 1st magnitude Jupiter is nearing the end of its 2019 appearance. By nightfall, it is only 9° above the western horizon. It sets at 5:14 PM and, in a week or two, be lost in the setting Sun’s glare. Saturn, shining with zero magnitude, lies about 2° above Venus on Monday, but the distance between them shrinks to 1.8° on Tuesday night. Saturn sets at 6:34 PM. Brightest Venus blazes with minus 4 magnitude between Saturn and Jupiter; it sets at 6:19 PM. Note that Venus rises higher daily, while Saturn sinks.

Neptune glows with 8th magnitude in Aquarius. By 9 PM, it appears about 35° high and 2 arc-seconds in size in the southwestern sky. It sets at 11:25 PM. Uranus, in Aries, shines with 5th magnitude and appears slightly brighter than Neptune. Tuesday night it inhabits Aries; this proximity to the Moon may hinder locating it. Uranus sets at 3:33 AM. Finder charts are available from astronomy web sites and magazines.

Civil Dawn brings Mars and Mercury sharing Libra. First magnitude Mars rises at 4:25 AM as a tiny 4 arc-second red dot. The Red Planet is preparing for its best appearance of the 2020’s in October. It will gradually become brighter and larger in our instruments. Mars appears very near the star Zubenelgenubi, also known as Alpha Librae. Mercury, brighter with zero magnitude appears about 5 arc-seconds in size and 86% lit. It is already slowly heading down and will be lost in the solar glare in about a week.

Every history student knows that December 7th marks the anniversary of the Japanese attack on Pearl Harbor. Few people are aware of the date’s astronomical significance. The Japanese high command chose that date because the eighteen-day-old Moon rose before midnight and shone at 87% permitting attack planes to launch in the dark and fly to their targets. However, the Moon almost helped foil the surprise raid. The Condor, an American minesweeper, spotted a submarine periscope silhouetted against the moonlight. The Condor called the Ward, a destroyer, who attacked a second submarine and radioed the incident to headquarters. However, that report was not heeded. Had that information been acted upon, the American fleet would have had at least an hour and a half to prepare.

This is Dudley Observatory’s Skywatch Line for Friday, December 6, through Sunday, December 8, written by Sam Salem.

On Friday, Sun rises at 7:12am and sets at 4:22pm; the waxing gibbous Moon rises at 1:46pm and sets at 1:14am. The Moon shines lower left of the Great Square of Pegasus on Friday night.

The date of earliest sunset depends on latitude, the farther north, the closer it occurs to the solstice. Earliest sunset of the year happens these days for our area (calculated at Schenectady latitude of 42.8 degrees N). The Sun sets at 4:22pm since December 2. It will set at 4:23 on December 16. This offset of the earliest sunset from solstice date (December 21) is balanced out by the opposite happening at sunrise. The Sun doesn’t come up its latest until January 2. The tilt of Earth’s axis and the eccentricity of Earth’s orbit cause this offset. For the southernmost U.S., around 30 degrees north latitude, the earliest sunsets of the year happen in late November. Closer to the Arctic and Antarctic Circles, the earliest sunset and earliest sunrise happen nearer the solstice.

Spot Mercury, at magnitude -0.6, low in the east-southeast as much as an hour before sunrise. Mercury is having its best dawn apparition of the year. Look for it very far below Arcturus. Mercury is closer to the lower left of fainter Mars and Spica. Mars, at magnitude +1.8 in constellation Virgo, is low in the east-southeast in early dawn. It sits to the upper right of Mercury. Brighter Spica shines farther upper right of Mars. This line of three expands farther each night as Mercury sinks lower and Mars and Spica get higher. Mars rises around 4:30am and Mercury rises few minutes after 5:30am.

Venus, at magnitude –3.9 in constellation Sagittarius, shines low in the southwest in evening twilight. It rises a little higher each week. Venus sets few minutes before 6:30pm. Jupiter, at magnitude –1.8, moves farther to the lower right of Venus in twilight. Jupiter sets almost an hour after sunset. It’s becoming difficult to spot before it sets. The gap between Venus and Jupiter increases from 6 degrees to 12 this week. Saturn, at magnitude +0.6 in constellation Sagittarius, is the steady yellow dot upper left of bright Venus. Every evening Venus gets about 1 degree closer to Saturn. The gap between them narrows from 13 degrees to 5 degrees this week. They’ll be just under 2 degrees apart on Tuesday and Wednesday next week. Saturn sets few minutes before 7pm.

Gerard Peter Kuiper was born on December 7 1905. The Dutch-born American astronomer discovered Miranda, a moon of Uranus, and Nereid, a moon of Neptune. The Kuiper Belt was named after his original suggestion of its existence outside the orbit of Neptune before it was confirmed as a belt of small bodies. Kuiper measured the diameter of Pluto. In 1947, Kuiper detected the existence of carbon dioxide and the absence of oxygen in the Martian atmosphere. In the 1960s, Kuiper served as chief scientist for the Ranger spacecraft crash-landing probes of the Moon. Ewen Whitaker, who worked under Kuiper, analyzed Ranger photographs and identified landing sites on the lunar surface most suitable for safe manned landings. Kuiper died in December 1973.

This is the Dudley Observatory Skywatch Line for Wednesday, December 4th, and Thursday, December 5th, written by Louis Suarato.

The Moon reaches its First Quarter phase at 1:58 a.m., Wednesday. Moonrise occurs at 1 p.m., and moonset is 14 minutes past midnight as a 65% illuminated, waxing gibbous Moon. Lunar apogee, when the Moon is farthest from Earth during this cycle, occurs at 11:08 p.m., Wednesday, when it will be 251,311 miles away. Saturn, Venus, and Jupiter span above the southwestern horizon at evening twilight. Jupiter will be the first to set at 5:33 p.m., followed by Venus at 6:14 p.m., and Saturn at 6:56 p.m.. Although the fewest total of daylight hours occurs on December 21st during the Winter Solstice, the earliest sunsets of the year take place between December 4th to the 14th, when the sun sets at 4:21 p.m. each day. Meanwhile, sunrises occur later, shortening the total amount of daylight. Look above the east-southeastern horizon for Mars, which rises at 4:24 a.m., and Mercury about an hour later. December 4th is the anniversary of the launching of the Mars rover, Sojourner, along with Mars Pathfinder, aboard a Delta rocket. Launched in 1996, Pathfinder and Sojourner reached the Martian atmosphere on July 4, 1997.

For a preview of the winter sky, look over the east-southeastern horizon after 8 p.m. to see the constellation Orion leaning back toward the Gemini twins. Orion contains two of the top ten brightest stars over our region. Rigel, at the foot of Orion, is the seventh brightest star, shining at magnitude 0.18. This blue supergiant star is a multiple star system estimated to be about 860 light-years away. Betelgeuse, located at Orion’s right shoulder, is a red supergiant star. This variable star is usually the ninth brightest star, but occasionally outshines Rigel, varying between magnitude 0.0 and 1.3, the widest variation of any first magnitude star. Orion is also the home of M42, the Great Orion Nebula. Located below Orion’s Belt, M42 is visible with the naked eye, even under some light-polluted conditions. A telescopic view of the Great Orion Nebula will reveal the Trapezium, a tight open cluster of stars. Discovered by Galileo in 1617, who sketched three stars, six stars of the Trapezium can be resolved with a five inch aperture or higher.

This is the Skywatch Line for Monday and Tuesday, December second and third, written by Joe Slomka.

The Sun sets at 4:22 PM; night falls at 6:03. Dawn begins at 5:27 AM and ends with the Sun rising at 7:08.

Monday’s Moon, in Capricornus, rose after Noon, is highest at 5:08 PM sets at 10:13 PM and is 39% illuminated. Tuesday’s Moon, in Aquarius, appears 47% lit, is highest at 5:53 PM and sets at 11:14 PM. The Moon turns officially “First Quarter” Wednesday at 1:58 AM.

Jupiter, Venus and Saturn, all in Sagittarius, continue to hug the western horizon. At about 40 minutes after sunset, Jupiter glows with minus 1st magnitude, but sits only 6° above the horizon; it sets at 5:35 PM. Venus, to Jupiter’s upper left, blazes with minus 4th magnitude appears about 49% lit and sets at 6:05 PM. Saturn, 11° to Venus’ upper left, shines with zero magnitude and is high enough for telescopic glimpses of its famous ring system, before it sets at 6:58 PM.

Night reveals Neptune and Uranus. Neptune, still in Aquarius, glows with 8th magnitude, is a tiny 2 arc-seconds in size, appears highest at 6:18 PM and sets at 11:53 PM. The nearby Moon may hinder observation with its brilliance. Uranus, in Aries, is brighter with 5th magnitude and appears a bit larger than Neptune. Its distance from the Moon may assist in observation. Uranus is highest at 9:13 PM and sets at 4:01 AM. Finder charts for these planets are available from astronomy magazines and websites.

Civil Dawn sees Mars, in Libra, about 20° high in the eastern sky. It displays a first magnitude red dot, about 4 arc-seconds in size. Mars rises at 4:29 AM. Mercury saw its highest point last week and is starting a rapid decline. Rising also in Libra at 5:26 AM, it shines with minus zero magnitude but appears larger than Mars and is 61% lit. The intrepid early morning observer should work quickly due to the brightening pre-sunrise sky.

French astronomer Pierre Mechain discovered M75 in 1780, in the constellation Sagittarius. He told his good friend comet hunter Charles Messier, who listed this object as number seventy-five in his list of comet lookalikes. In 1784, British astronomer William Herschel estimated the distance to this “nebula without stars” as six thousand light-years. We now know that M75 is a globular star cluster. Globular clusters are usually found around galaxy halos and Globulars bulges. Globulars may contain up to a million stars and are quite large, in a sphere about 100 light-years across. These stars are quite old. Modern estimates place M75 at about fifty-nine thousand light-years away. Astronomers also describe it as one of globulars compact globulars in the sky. Only the largest telescopes can resolve the cluster into individual stars.

This is Dudley Observatory’s Skywatch Line for Friday, November 29, through Sunday, December 1, written by Sam Salem.

On Friday, Sun rises at 7:04am and sets at 4:23pm; the waxing crescent Moon rises at 10:00am and sets at 7:13pm. The crescent Moon appears 2 degrees to Saturn’s left on Friday evening. The two stand some 15 degrees above the southwestern horizon, an hour after sunset. They make a pretty pair with the naked eye or through binoculars.

Mercury reached its greatest elongation from the Sun on Thursday. The planet is 20 degrees west of the Sun, visible in the eastern sky at dawn, not far from Mars and the bright blue-white star Spica in the constellation Virgo. Spot Mercury low in the east-southeast in early dawn. It’s far to the lower right of similarly bright Arcturus, by about 30 degrees, or three fists at arm’s length. Mercury rises at 5:17am, on Friday. Mars, at magnitude +1.8 in constellation Virgo, is low in the east-southeast in early dawn, to the upper right of Mercury. Mars is roughly halfway from Mercury to Spica. Mars rises around 4:30am

Venus, at magnitude –3.9, and Jupiter, at magnitude –1.8, shine together low in the southwest as twilight fades. They both sit in constellation Sagittarius. Venus is the brighter one. Every evening their orientation changes a bit. Jupiter moves away to Venus’s right and lower right. Venus sets few minutes after 6pm and Jupiter sets few minutes before 6pm. Saturn is the steady yellow object some 20 degrees upper left of brighter Venus and Jupiter. Venus draws a little closer to it each evening. They’ll reach conjunction on December 10th. Saturn shines at magnitude 0.6, more than a full magnitude brighter than any of the background stars in its host constellation Sagittarius. Saturn sets few minutes after 7pm.

The stars of both summer and winter appear prominent in late evenings of Thanksgiving weekend. If you look toward the west around 9pm, you’ll see the bright stars of the Summer Triangle. Vega still shines brightly well up in the west-northwest after dark. The brightest star above it is Deneb, the head of the big Northern Cross, which is made of the brightest stars of Cygnus. At nightfall the shaft of the cross extends lower left from Deneb. Turn around and face east, you’ll find stars normally associated with winter. Betelgeuse, Rigel, Aldebaran, and Capella all appear conspicuous around 9pm. The Big Dipper swings low in the north at this time of year. Although this asterism never sets from much of the United States and Canada, it does come close. As the stars come out, the W shape constellation Cassiopeia stands on high in the northeast. Watch Cassiopeia turn around to become a flattened M, even higher in the north, by late evening.

This is the Dudley Observatory Skywatch Line for Wednesday, November 27th, and Thursday, November 28th, written by Louis Suarato.

The 2% illuminated, waxing crescent Moon sets at 5:35 p.m., Wednesday. Look to the Moon’s upper left for Venus and Jupiter separated by 4 degrees. Venus will be the brighter of the two planets. Higher, and further south, shines Saturn in the constellation Sagittarius. Thanksgiving provides a photo opportunity of a fine conjunction of the Moon in proximity of the two planets, when the crescent Moon will be 2 degrees above Venus. The 6% illuminated, waxing crescent Moon will set at 6:24 p.m., Thursday. Thursday, Venus will reach aphelion, its furthest distance from the Sun during its annual orbit. At aphelion, Venus will be 67.67 miles from the Sun. Venus is currently 133.856 million miles from Earth. According to NASA, Venus is 162 million miles from Earth at its furthest when both planets are on opposite sides of the Sun. The pre-dawn sky rounds out the easily visible planets by providing views of Mars and Mercury. Look above east-southeastern horizon after 5:30 a.m. for the two planets. Mars will be the higher, and dimmer of the two. On November 28, 1964, Mariner 4 was launched from Cape Kennedy, Florida. On July 14, 1965, Mariner 4 made its Mars fly-by, and became the first satellite to transmit a close-up photograph of Mars. Flying as close as 6,118 miles, Mariner 4 revealed Mars to have a cratered, rust-colored surface. The star above Mars is Spica, Virgo’s brightest. Mercury rises at 5:15 a.m. in Libra.

Thanksgiving also gives us a bright, 1st magnitude International Space Station pass over our region. Beginning at 5:02 p.m., look over the western horizon for the ISS to emerge from the fading glow of sunset. The conjunction of the Moon, Venus and Jupiter will be to the south of the rising ISS. The Space Station will then head northwest toward the constellation Hercules. After the ISS passes under Hercules, it will head toward Ursa Minor. The ISS will then pass under the Little Dipper and onto the northeast horizon, passing Capella in the constellation Auriga on the way. You may be able to capture the rising ISS and the conjunction in the same field of view with a wide-angle lens.

This is the Dudley Observatory Skywatch Line for Monday, and Tuesday, November 25th and 26th, written by Joe Slomka.

The Sun sets at 4:32 PM; night falls at 6:25. Dawn begins at 5:19 AM and ends with Sunrise at 6:49.

Monday’s Moon sets at 4:07 PM; Tuesday’s Moon sets at 4:45 PM and turns officially “New” at 10 AM.

About 40 minus after Sunset, Venus and Jupiter lie close together and low to the southwestern horizon. On Tuesday’s Dusk, they are positioned 3° apart with Jupiter lowest. Venus, Jupiter and Saturn share the constellation Sagittarius. Venus and Jupiter set at 5:56 PM; Saturn hangs on for another 2 2/3 hours before setting at 7:23 PM. Even though low on the horizon, its maximum tilt to us permits views of its glorious rings. In the coming weeks, note how Venus gradually sneaks up on Saturn.

Neptune, in Aquarius, sets at 12:24 AM. Uranus, in Aries, is best seen at 9:41 PMand sets at 4:30 AM. Both appear as tiny blue-green dots amid the stars. Binoculars or telescopes assist in finding them, along with finder charts from astronomy magazines and websites.

Mars rises at 4:32 AM in Virgo as a first magnitude red dot 4 arc-seconds in size. Mercury in nearby Libra rises at 5:16 AM. Wednesday’s dawn sees Mercury only 2° from Spica, the brightest star in Virgo.

Since 2004, the Cassini space probe has been circling Saturn. While the planet was the main focus of the mission, the probe also studied the largest moon in our Solar System, Saturn’s Titan, over 5100 km in diameter. Using radar and infrared sensors, the probe mapped the giant satellite; NASA released the map earlier this week. It turns out that Titan has the same geologic processes as Earth. Equatorial dunes are not made of sand but hydrocarbons; the dunes can be as high as the Statue of Liberty. Hydrocarbon lakes gather around the poles. Plains constitute 2/3 of Titan’s surface. Labyrinths, craters and hummocks fill out the inventory.

Winters in the Northeast are notoriously cloudy. However, when skies are clear, the night sky presents a riot of brilliant stars and constellations that seem close enough to reach out and touch. In fact, twenty-three of the fifty brightest stars are visible in tonight’s sky. Orion, the Dogs and Taurus account for the majority of the brightest stars in the heavens. Sirius is not only brightest on this list, but also second only to the Sun in luminosity; it is also the leading light of Canis Major, the Large Dog. About half of the list lies relatively close to us; the other half is intrinsically brighter, though further away. So, if it is clear, bundle up and enjoy Nature’s sky show.

This is Dudley Observatory’s Skywatch Line for Friday, November 22, through Sunday, November 24, written by Sam Salem.

On Friday, Sun rises at 6:56am and sets at 4:27pm; the waning crescent Moon rises at 1:51am and sets at 2:35pm. The Moon reaches perigee, the closest point in its orbit around Earth, at 2:41am on Saturday. It then lies 227,867 miles away from Earth. Moon, Mars, and Mercury form large triangle in morning twilight on Sunday.

On Saturday, Venus is 1.5 degrees lower left of Jupiter in evening twilight. Jupiter lies above Venus on Sunday night, Venus appears to the left and slightly below Jupiter. The best views of this conjunction will come with the naked eye or binoculars. Venus sets few minutes before 6pm and Jupiter sets few minutes after 6pm.

Saturn resides among the background stars of constellation Sagittarius the Archer. Saturn shines at magnitude 0.6 and appears significantly brighter than any of its host constellation’s stars. A small instrument shows Saturn’s 16″-diameter disk and spectacular ring system, which spans 35″ and tilts 25 degrees to our line of sight. Saturn sets around 7:40pm.

The waning crescent Moon makes a convenient guide for spotting Mars, at 1.7 magnitude, on Sunday morning. Look for the 6-percent-lit Moon about 15 degrees high in the east-southeast an hour before sunrise. The Red Planet lurks 4 degrees to Moon’s right. Look for magnitude –0.4 Mercury, 8 degree below the Moon. Mars rises around 4:30am and Mercury rises around 5:20am.

Try to spot Uranus, at 5.7 magnitude, with the naked eye this weekend. Uranus, in southern constellation Aries, is well up in the east by 8pm and highest in the south around 10pm.

The Andromeda Galaxy, Messier 31, can be seen with the naked eye as a hazy dash of light directly overhead around 9pm from a dark-sky site. Look for it atop a stack of three modestly bright stars in Andromeda. Start with second-magnitude Beta Andromedae. Look above that to Mu Andromedae, then above Mu to Nu Andromedae. Directly above Nu, the Andromeda Galaxy shows as a fuzzy, elongated slant of light of magnitude 3.4. From a very dark site, M31 may appear 0.5 degree across, about as wide on the sky as our Moon. Telescopic observers can also see M32 and M110, M31’s elliptical satellite galaxies. Andromeda Galaxy is 2.5 million light-years away. In 1925, astronomer Edwin Hubble was the first to resolve its variable stars, using Mt. Wilson’s 2.5-meter telescope to prove M31 is a gigantic galaxy like ours.

Later at night, enjoy the sight of some fine double stars in the constellations Andromeda and Aries. Gamma Andromedae, or Almaak, is an excellent example of contrasting colors within a binary star system. Like Albireo of our summer nights, Gamma Andromedae’s two main stars shine orange and blue. The fainter blue component is itself a binary, but at magnitude 5.0 splitting this close pair may not be easy even at high magnification. The brighter star is a K-type giant of magnitude 2.3. Star’s color is dependent on its surface temperature. The orange-tinted star is the cooler of the two, while the bluish component radiates hotter. Just below Almaak is Gamma Arietis. This binary features blue-white stars shining at 4.6 and 4.7 magnitude, an almost evenly matched pair of hot, A-type stars. Astronomer Robert Hooke was the first to describe this double in 1664.

This is the Skywatch Line for Monday and Tuesday, November 18th and 19th, written by Joe Slomka.

The Sun sets at 4:30 PM; night falls at 6:09. Dawn begins at 5:13 AM and ends with the Sun rising at 6:52.

The waning Monday’s Moon rises in Taurus at 10:12 PM, is highest at 10:45 PM and sets at 1 PM Tuesday. Tuesday’s Last Quarter Moon rises in Leo at 11:24 PM and sets at 1:35 PM, Wednesday.

Civil Twilight finds Jupiter and Venus still visible about 40 minutes after Sunset. Venus, in Ophiuchus, is lower on the southwest horizon and about 11 arc-seconds in size, but a brilliant minus 4th magnitude; Jupiter, in Sagittarius, lies to Venus’ upper left, is less bright but almost 3 times Venus’ size. Venus sets at 5:47 PM, Jupiter at 6:17.

By 9 PM, Neptune, in Aquarius, glows with 8th magnitude and appears about 2 arc-seconds in size and is highest at 7:13 PM. Uranus, in Aries, is brighter with 5th magnitude, appearing a bit larger than Neptune and is highest at 10:10 PM. Neptune sets at 12:52 AM, Uranus at 4:59 AM.

Binoculars or telescopes are recommended for all four planets, as well as finder charts for Uranus and Neptune.

Mars rises in Virgo at 4:36 AM and shines with first magnitude and almost 4 arc-seconds in size. Mercury, fresh from its spectacular transit across the Sun, and beginning a Dawn visit, now rises in Libra at 5:38 AM, shines with first magnitude, but appears larger than Mars. Wednesday’s pre-dawn has a dramatic alignment of Mercury, Mars and Virgo’s brightest star, Spica. Early observers are advised to be out about 1 hour before Sunrise.

The Leonid meteor shower peaked early Monday morning; however, sky watchers may see stragglers during Tuesday’s night and dawn.

Even though the New Horizons space probe is racing through the Kuiper Belt, its discoveries still become news. Last week, the final object that New Horizons studied, asteroid 2014 MU69, was officially renamed. The New Horizons staff, with the permission of the Powhatan/Algonquian tribe, submitted to the International Astronomical Union a petition to rename MU69. Its new official name is Arrokoth, which translates “Sky.” The New Horizons staff are located in Maryland, which was Powhatan native land, so it was felt that their sky lore should be recognized.

Followers of the Skywatch Line know that the Milky Way, which tonight stretches from horizon to horizon, represents the rim of our galaxy. They also know that the faint glow in Andromeda is that of a giant galaxy, similar to ours. However, these “island universes” are not isolated from each other. Their gravitational fields clump galaxies into groups. The Local Group is made of our Milky Way, Andromeda, M 33 in Triangulum, and about a dozen other galaxies. This group is traveling together through space. Some galaxies also interact with each other. A prime example is M 51, off the Big Dipper’s Handle. A telescope shows one galaxy stealing material from another. Some astronomers think that giant galaxies like our own grow by absorbing smaller ones. Colliding galaxies are common telescopic sights. It is thought that two spiral galaxies will merge to form an elliptical galaxy. In fact, in about three billion years, Andromeda and the Milky Way will probably collide and merge. The result will be a giant galaxy marked by very active star formation.