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October Night Sky

October 2011 Night Sky

Charlie Christmann

Aren’t the Moons Lovely Tonight?

What! Moons? Yes, moons. A recent theory suggests that Earth may at one time have had two moons. This thinking dovetails into the theory that a Mars-sized object once collided with Earth not long after its formation 4.5 billion years ago, blasting material into orbit. Until recently, that debris was thought to have coalesced into the one moon we see today. Not all scientists agree with this idea, but agree it could be plausible.

But, there are two points in orbit around Earth, with the moon, that are relatively stable. The Lagrangian points, or Trojan points, lead and lag the moon by 60 degrees. Here, gravity of the Earth and moon offset and allow objects to persist in those locations for a long time. Material from the collision could have gathered into a small moon at one of those Lagrange points. Over tens of millions of years, with the moon slowly moving to a higher orbit, and the sun’s gravitational pull, the smaller moon would have migrated out of the Lagrange point.

The mystery started when scientists saw a distinct difference between the Earth-facing side and the far side of the moon. The far side is much more mountainous with a thicker crust layer. The near-side is dominated by the mare lowlands. Another question that needed to be answered was why Earth had always been an oddball in the solar system. It is a planet with a single moon; Venus and Mercury have no moons, Mars has two, while Saturn and Jupiter have more than sixty each. Even tiny Pluto has four moons. Why do we have just one?

As the smaller moon, some think it may have been 600 miles across, was dragged toward the larger moon. The collision was extremely slow, taking at least 10 minutes to complete. At these low speeds, rocks don’t melt and big craters don’t form. The smaller moon just splatters onto our current moon. The whole event took less than a day. The remains of this Trojan moon would make up the highlands now seen on our moon’s far side. At the same time, the impact would have pushed the internal ocean of magma, remaining from the moon’s original formation, toward the near side, explaining why rare-earth metals and radioactive elements are more abundant on the Earth-facing side.

NASA’s twin lunar Gravity Recovery and Interior Laboratory (GRAIL), now on its way to the moon, will attempt to solve the two-moon question. GRAIL will measure the gravity field of the moon by recording the distance between the two spacecrafts to about a millionth of an inch. Using those measurements, scientists will then be able to infer the internal structure, which allows them to make more accurate assumptions on how structures such as basins and craters were formed.

Terrestrial Trojans

Like the Earth-moon system has Lagrange points, so does the Earth-sun system. In October 2010, using data from NASA’s Wide-field Infrared Survey Explorer (WISE) satellite, a Trojan was spotted ahead of the Earth in our orbit around the sun. That asteroid, named 2010 TK7, is held in a delicate balance between a gravitational tug from the sun and an equal tug from the Earth. It orbits the Lagrange point 60 degrees in front of the Earth, ranging from 49.7 million miles to 12.4 million miles away. The composition and surface characteristics of TK7 are unclear, though it is believed to be several hundred feet in diameter and may be a chunk left over from the event that caused the formation of the moon. Computer modeling indicates that it will stay in its orbit for at least 10,000 years. Over time astronomers expect to find other Trojans near these islands of gravitational stability.

Orionid Meteor Shower

The annual Orionid meteor shower peaks on the 21st this month. Expect a maximum of about fifteen meteors per hour with the best viewing after midnight. These fast-moving meteors occasionally leave persistent trains and bright fireballs.

The Planets and Moon

  • Mercury is low in the west-southwest just after sunset.
  • Venus is just above Mercury, low in the west-southwest after sunset.
  • •Mars rises in the east between 2:00 a.m. and 1:30 a.m. Mars will be seven degrees to the upper left of the waning crescent moon on the 21st.
  • Jupiter will be low in the east after sunset. Look for Jupiter sex degrees to the right of the waning gibbous moon on the 13th.
  • Saturn will be up during daylight hours this month.
  • The Moon is full at 8:06 p.m. on the 11th and new at 1:56 p.m. on the 26th. There is a moon-Pleiades conjunction on the 14th.
  • Beware of UFOs (Unusual Flying Objects) on the 31st. This could be one scary evening.

Rio Rancho Astronomical Society members (left to right) Alan Parrish, Darin Templet, Rachel Templet, Roxanne Blatz and Melanie Templet at the observatory of the late Walter Hiltbrunner, creator of the scopes.

RRAS presents “A Night Under the Stars”

—Rio Rancho Astronomical Society

The Rio Rancho Astronomical Society (RRAS) presents A Night Under the Stars, a fundraising event on Saturday October 15 at Rainbow Park, 301 Southern Boulevard. The event will include food, live music, and a silent auction.

RRAS has acquired three research-grade telescopes: a 12.5 inch Newtonian, a 16 inch Cassegrain, and a 25 inch Obsession Dobsonian. The latter offers enough light gathering ability as to show the colors of the bands on Jupiter.

The October 15 event will be the first of several fundraising events. Doors open at 5:30 p.m.  Food will be available at 6:00. Auction bidding will close at 7:00 p.m. and winners will be posted at around 7:20 p.m.

Entertainment will be provided by the Muddy River String Band, an Albuquerque based Americana band. From folk to blues, bluegrass to old-time, Celtic to Cajun, their unusual instrumentation includes the hammered dulcimer and the cello.

There will be a wide variety of items to place bids on in the silent auction.

Tickets for this event can be purchased online at or at the door. Children up to 3 years are free.  Children four to twelve years old are $5. Adults thirteen years and above are $10 online or $15 at the door. For more information, please see our website at

Stargazers in for a treat on October 22 in Placitas

On Saturday, October 22 Las Placitas Association, the Placitas Community Library, and the Albuquerque Astronomical Society (TAAS) will co-host a free public astronomical viewing event at the Placitas Community Library. This will be the first star party held at the new Placitas Community Library and considering its altitude at well over a mile above sea level, one can expect dark moonless skies making for fantastic viewing conditions.

The event begins at 6:30 p.m. and will officially end at 10:30 p.m. Volunteers will be on hand to assist the pubic and astronomers with parking. Amateur and professional astronomers and anyone else wishing to bring telescopes should to arrive before 6:00 p.m. for setup in the paved parking lot found along the southern side of the library. Visitors will park in the gravel area immediately west of the library.

On Saturday, Jupiter will be rising high by 9:00 p.m. and will be flaunting its four Galilean moons. The distant icy giant planets Uranus and Neptune will also be well placed for viewing. Much further beyond our solar system, viewers can expect to see innumerable “diamonds on black velvet”—stars bound within the great Hercules and Wild Duck Star Clusters. Moving ever deeper, discern the tenuous wisps of the energized Dumbbell and Ring Nebulas. And finally, well beyond our own galaxy, trace the fuzzy edges and bright cores of sister galaxies within our own “local group” including Andromeda and her orbiting satellite galaxies Messier 32 and 110.

Inside the library, astronomers will be presenting information on several current “hot topics” in astronomy. The library will provide hot beverages and indoor bathrooms.

Don’t forget your red flashlights as white light knocks out night vision needed to see stars and deep sky objects. Red cellophane works well to redden white lights. As always, this event is weather-dependent.





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