SKY REPORTER: November 2011
by Steve Beyer on
Tuesday November first civil twilight begins at 6:57 a.m. and sunrise is at 7:26. That evening the Sun, located in the constellation Libra, sets at 5:52 p.m. Civil twilight concludes at 6:21.
Civil twilight starts at 6:13 a.m. and sunrise is at 6:42 a.m. Tuesday, November 15th. That day sunset occurs at 4:38, with civil twilight concluding at 5:07 p.m.
On the last day of the month, Wednesday November 30th, civil twilight begins at 6:29 with sunrise at 6:59 a.m. Sunset is at 4:29 and civil twilight ends at 5:00 p.m.
During November average overnight temperatures recorded in Central Park drop from 45 degrees Fahrenheit on the first of the month, to 36 degrees on the 30th. On that day the Sun is located in the constellation Ophiuchus.
Principal Phases of the Moon this month are:
|First Quarter||November 2|
|Full Moon||November 10|
|Last Quarter||November 18|
|New Moon||November 25|
Daylight Saving Time ends at 2 a.m. Sunday November 6th.
Tuesday November 1st, a wide crescent moon and planets Mercury, Venus, and Jupiter are all above the horizon at sunset. Mercury and Venus remain low in the western sky during civil twilight through the first half of the month. Then Mercury begins to set even sooner after sunset while Venus moves further eastward, setting nearly two hours after sunset by the end of the month. In November Jupiter dominates our sky throughout the night. At the start of this month Mars is in Leo and rises an hour and ten minutes after midnight. Saturn, in the constellation Virgo, rises at 6 a.m. on November 1st.
During November comet Garradd continues to brighten, but at magnitude 6 it is difficult to sight with unaided eyes even under a very dark clear sky. However, using binoculars you may be able to see it, even from urban locations. The comet is currently about five degrees of arc east of the midpoint of a line between stars Alpha and Delta in the constellation Hercules. At 7 p.m. on November 1st, face west and look for the comet halfway between the horizon and zenith. At that time during mid-month its altitude above the horizon is about 20 degrees, or two fist lengths when seen at arm’s length. At 7 p.m. on the last day of November, the comet will be 11 degrees above the west-northwest horizon. It was discovered two years ago by Australian Gordon Garradd.
The evenings of Tuesday and Wednesday November 8th and 9th look for a bright gibbous moon in the neighborhood of Jupiter. It is usually difficult to distinguish the wide gibbous phase from a Full Moon, and the perception of seeing a Full Moon may transcend several nights each month just before and after the actual event. If you have never identified Jupiter in the sky, the moon these nights provides a fine guide to the big planet’s identity. One of the most intriguing and beautiful sights a telescope can offer is Jupiter and its retinue of large moons: Io, Europa, Ganymede, and Callisto. On the evening of November 8th Io is situated east of Jupiter’s disk and the other three Jovian moons are just west of the planet.
November’s Full Moon occurs on Thursday the 10th. Two of its traditional names, Full Beaver moon and Full Frosty Moon aptly describe natural events typical of this month in our part of the country. The big and endearing woodland rodents, among the earliest icons of New York City, are making last minute additions to their lodges before the onset of frost.
Friday evening November 11th a waning gibbous moon may be seen half way between the Pleiades and Hyades open star clusters in the constellation Taurus. The Pleiades cluster is also referred to as the “Seven Sisters,” or “Messier 45.” Use of the Hubble Space Telescope helped refine the distance of this cluster to be about 440 light-years from the Solar System. Although sharp eyed observers may see a handful of Pleiades stars without optical assistance, the cluster actually contains about 1,000 members.
Triangulation of representative Pleiades stars, measured from opposite sides of Earth’s orbit, is used to determine this cluster’s distance by the parallax method. The size scale of the entire observable universe largely rests on knowing distances of the Pleiades and Hyades clusters. Correlations between luminosity and colors of individual stars in these groups then are used to estimate distances of more remote clusters known to have similar luminosity and color distributions, but whose stars appear diminished in brightness due to their greater distances.
The most vivid stars in both Pleiades and Hyades may be seen with unaided eyes, and binoculars or wide-angle telescopes provide wonderful views of both clusters.
The Moon also serves as a visual guide to more distant open star clusters. Monday November 14th the Moon in its waning gibbous phase is near the direction of clusters Messier 35 and NGC 2158 in the constellation Gemini, each containing about 2,500 stars. Respective ages for these clusters are 150 million and one and a half billion years. Binoculars reveal M35 and a small telescope may also show NGC 2158.
M35 is about 2800 light years from the Solar System and NGC 2158 has a distance of approximately 11,000 light years. These distances are largely determined by comparisons of color and brightness distributions of the clusters’ stars with those of the Hyades and Pleiades.
The early morning of Saturday November 19th a wide waning crescent Moon is eight degrees of arc south of first magnitude Mars. The red planet currently is about 133 million miles from Earth.
Tuesday November 22nd Saturn, Spica and a crescent Moon are in the pre-dawn sky about 20 degrees of arc above the southeast horizon at 6 a.m. Saturn is eight degrees to the left of the Moon with the first magnitude star Spica halfway in between.
On Saturday evening November 26th the very narrow day and a half “old” crescent moon is five degrees to the right of Venus and about eight degrees above the southwest horizon at 5 p.m. Due to the low altitude of both Venus and the moon an unobstructed view of the western horizon is required. Remember, the length of a fist seen with arm fully extended spans approximately ten degrees of arc. We often refer to the position of the moon on a particular night as a guide to locating and identifying planets or other celestial features. During twilight this evening, 40 hours after the moment of new moon, we reverse our usual process and use the planet Venus, brilliant at magnitude minus four, to help catch a view of the “young” moon. Binoculars will help when making this observation. For viewing objects near the horizon it is a good idea to search for suitable viewing sites during daylight well before anticipated times of your observations.
Sunday evening November 27th, a wider lunar crescent is nine degrees to the upper left of Venus, and 17 degrees above the southwest horizon at five p.m.
At five o’clock on the afternoon of November 30th Mercury is setting and Venus is about 10 degrees above the southwest horizon. That night Mars rises at 11:26 p.m., Saturn rises at 3:23 a.m. and Jupiter sets at 4 a.m.
During November a brilliant array of stars, typically seen during evenings of late autumn and winter, begins to appear above the eastern horizon, as stars usually associated with summer nights sink lower in the western sky.
At nine p.m. Tuesday November 15th, the Milky Way’s Band arches across our sky from east to west, passing two-thirds of the way up from the northern horizon toward the zenith. At its midpoint in the constellation Cassiopeia, we look through the Galactic disk in a direction away from the Milky Way’s center in Sagittarius. It was in Cassiopeia during 1572 that Danish astronomer Tycho Brahe made a remarkable discovery that launched his career as the greatest observational astronomer before the telescope’s invention. Tycho demonstrated that a brilliant star, that suddenly had become visible in Cassiopeia, was located further from Earth than the Moon. It provided first evidence that changes can occur in the supposedly immutable celestial realm. The object Tycho studied was what is now known as a type Ia supernova.
In the Milky Way Galaxy, at a distance from us estimated at between 8,000 and 10,000 light years, the Tycho supernova resulted from the explosion of a white dwarf star that over time had attracted such a great extra burden of mass from a stellar neighbor that the added weight could not be supported by the dwarf’s internal structure. A devastating collapse and explosion resulted. When that happens, a former white dwarf becomes a dazzling type Ia supernova with a well-known luminosity. These spectacular events serve astronomers as “standard candles” providing a reliable way of calculating distances to new examples of such dramatic cataclysms. The process is similar to knowing the luminosity of a 100 watt light bulb and, when seeing such a light from afar, being able to measure its diminished brightness, and then calculating the bulb’s distance.
During the 1990’s, using observations of many type Ia supernovae seen in extremely distant galaxies, two teams of astronomers independently discovered shocking evidence that the expansion of the observed universe is accelerating rather than decreasing as was expected. The cause of this phenomenon is called “dark energy” and may be thought of as a kind of anti-gravity. Astonishingly, dark energy is believed to constitute over two thirds the content of the universe. Last month leaders of both research endeavors, Saul Perlmutter of the Lawrence Berkeley National Laboratory in California, Brian Schmidt of the Australian National University, and Adam Riess of the Space Telescope Science Institute and Johns Hopkins University were awarded the Noble Prize in Physics for their discovery of the universe’s accelerating expansion.
The constellation Cassiopeia represented the queen of Ethiopia in Hellenic legends of Andromeda, Perseus and the Royal Family of the Sky. The brightest stars of Cassiopeia form an asterism that may be seen as a “W” or an “M”, depending on the time and date of your observation. This figure is on the opposite side of Polaris from the Big Dipper in our northern sky. Cassiopeia is nearest our zenith during autumn and the Big Dipper is at its maximum altitude during the spring season.