Celestial
Lights
By
Phyllis Pitluga, Nov
3, 2006
Rare
passage of Mercury across the face of the Sun, November 8
The
planet Mercury will be orbiting between the Earth and the Sun, passing across
the Sun as a mini-mini-eclipse, called a transit. Every 116 days, Mercury passes
the Sun, but it is usually above the Sun or below it. The last time Mercury
crossed in front of the Sun was in 2003, and the next transit will be in 2016.
(Even though Mercury orbits the Sun in 88 days, we are also moving on our
orbiting Earth. The combination of our relative motions is what creates the
116-day passages of Mercury.)
Mercury
will first appear as a dark, tiny dot slowly moving across the left edge of the
lower half of the Sun at 1:12pm. By 3:41pm, Mercury will be halfway across, and
by sunset Mercury will still be transiting the Sun (people west of us will see
Mercury move off the face of the Sun).
Observing
Mercury crossing the Sun is a wonderful opportunity to see the comparative sizes
of a planet two and a half times smaller than Earth against our giant star—the
Sun. This transit also reveals the slow majesty of orbiting worlds.
Anytime
you look directly at the Sun you will permanently burn a spot into your eye. To
safely see this transit or to observe sunspots, you need a solar filter in front
of a telescope, or the Sun’s image can be projected out of a telescope or
binoculars onto a white screen.
Leonid
meteor shower
November 18
Every
year there are more than a dozen meteor showers, approximately half of which
aren’t blotted out by bright moonlight. This year, with a waning Crescent
Moon, the Leonids should be exceptional from dark-sky sites.
Starting
about 10:30pm, let your eyes adapt to the darkness of night and you will see
ever fainter stars and meteors. Look toward the eastern sky for the next couple
of hours. For meteor showers you do not need binoculars or telescopes—just
observe with your eyes.
The meteor shower particles are grains of sand from comets that have orbited the Sun many times so that their cohesive ices have evaporated, leaving a trail of rocky grains. The Leonid shower is what remains of Comet Temple-Tuttle (named after the comet discoverers of 1865–6). Every mid-November the Earth orbits through this debris field. The comet grains heat up from friction with Earth’s upper atmosphere, creating the glowing trails across our sky. These grains burn up and do not reach the surface of the Earth. So settle back in a chaise and let the “shooting stars” be your Saturday night entertainment.
Sky Calendar, November 2006
By
following the Moon as the biggest and brightest “pointer” in the sky, during
the month you can identify different planets and bright stars. On following
nights you can relocate them but without the Moon—the Moon moves about 25
times its own diameter from one night to the next.
The
Moon is much closer than the planets of our Solar System; the stars are even
farther away. So, when the Moon appears close to celestial lights they are truly
separated by millions, billions or trillions of miles.
Sunday,
November 5: The Full Moon rises at sunset. For the next two weeks, the Moon
rises about 50 minutes later each night, making it also visible in the morning
sky as the Moon orbits toward the direction of the Sun.
Monday,
November 6: The waning Gibbous (shrinking, oval-shaped) Moon passes
half-a-moon-diameter above the Pleiades Star Cluster.
Wednesday,
November 8:
The planet Mercury passes in front of the Sun.
Sunday,
November 12:
The Last Quarter Moon rises after midnight.
Monday,
November 13:
The waning Gibbous Moon passes three moon-diameters above Saturn.
Friday,
November 17:
The waning Crescent Moon passes one-moon-diameter beneath the bright star Spica
of the constellation of Virgo in the dawn sky.
Saturday,
November 18:
Leonid meteor shower.
Sunday,
November 19:
the slender waning Crescent Moon passes 12-moon-diameters below the planet
Mercury in the dawn sky.
Monday,
November 20:
New Moon (= no Moon because the dark side faces Earth).
Saturday,
November 25:
Mercury will be highest up in the morning sky for the year (from Earth we see
Mercury appear to swing from one side of the Sun to the other). If you
identified Mercury on November 19 when the Moon was passing beneath it, you will
easily see it as a bright, shimmering point of light.
Sunday,
November 26:
The waxing Crescent Moon passes six-moon-diameters beneath the telescopic planet
Neptune.
Tuesday,
November 28:
First Quarter Moon (halfway across the sky at sunset) passes below the
telescopic planet Uranus.
Phyllis
Burton Pitluga is Astronomer Emerita of the Adler Planetarium and Astronomy
Museum, Chicago, and is now a San Miguel resident.