Bella is having a very bad day and is not up for remembering her astronomy.

Bella is having a very bad day and is not up for remembering her astronomy.

Today is the new moon. A different New Moon happens Friday, when the second movie made from Stephenie Meyer’s popular Twilight book series opens in theaters.

Although Twilight fans may not care, our heroine Bella Swan’s knowledge of lunar phases is questionable. In the book’s title-inspiring scene, in which her vampire boyfriend Edward leaves her and she wanders through the woods for hours, Bella thinks, “Tonight the sky was utterly black. Perhaps there was no moon tonight—a lunar eclipse, a new moon.”

Bella correctly equates “new moon” with “no moon.” A new moon is above the horizon only during the day, and the only lit part is the far side that we can’t see.

But Bella’s phrasing suggests a few astronomical impossibilities:

1) In her distress, is Bella thinking a lunar eclipse and new moon are the same? Her thoughts are ambiguous. But a lunar eclipse can happen only when the moon’s phase is full. Never when it’s new. Not even in fictional worlds with vampires.

When the moon is new, it’s between the sun and Earth, as Meyer describes on her Web site. A lunar eclipse, however, requires a different geometric line-up: Sun-Earth-Moon.

Lunar eclipse geometry

Only in this configuration can the Earth’s shadow cover (eclipse) the moon. MrEclipse.com explains why lunar eclipses don’t happen every full moon, and NASA’s lunar eclipse page lists dates of past and future lunar eclipses.

2) Even during a lunar eclipse, Bella wouldn’t have “no moon tonight.” The moon remains visible when eclipsed by the Earth’s shadow. Although the moon darkens, sometimes almost to the point of invisibility, it won’t completely disappear because Earth’s atmosphere bends sunlight. An eclipsed moon usually looks reddish (not to be confused with the reddish tint the moon can take on when near the horizon, regardless of its phase).

This total lunar eclipse did not happen at new moon. (Credit: Fred Espenak)

This total lunar eclipse did not happen at new moon. (Credit: Fred Espenak)

3) Even with no moon, the sky wouldn’t look “utterly black” in Forks, Washington, where Bella wanders the woods, unless there was a regional power outage. Because of light pollution, there are no truly dark skies in the entire state. But we can forgive Bella for exaggerating in her distraught condition.

Six months later (warning! spoiler ahead!), things brighten up for Bella when she reunites with Edward in Italy. There they further mangle the solar system by experiencing an impossible sun. That’ll be another blog post.

Do you have an example to share of impossible astronomy in a book?  Please post a comment.

Amy Sayle is Morehead's Science 360 manager. She doesn't let impossible astronomy get in the way of enjoying a good story.

MESSENGER took this image of Mercury on September 29, 2009, during its third flyby.  This image shows portions of the planet’s surface never seen before by spacecraft.  (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

MESSENGER took this image of Mercury on September 29, 2009, during its third flyby. This image shows portions of the planet’s surface never seen before by spacecraft. (Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington)

Early tomorrow morning (Thursday, October 8th) will be a good time to spot a rarely seen planet—Mercury.

About 45 minutes before sunrise, look for Mercury low in the east and hanging out just a smidgen below and to the right of Saturn. You’ll need an unobstructed horizon because even at its best placement in the sky, Mercury never appears far from the Sun.

Mercury is not only rarely seen by humans, it hasn’t been seen much by our spacecraft either.  NASA’s MESSENGER spacecraft, which recently flew by the planet, is only the second to visit Mercury, and in March 2011, it will be the first to orbit it. Mercury’s first visitor, Mariner 10, flew by the planet in 1974-75.

The scientific goals of the MESSENGER mission include answering questions such as why is Mercury so dense and what is its geological history and the nature of its magnetic field. You can learn more about this mission at NASA’s MESSENGER Web site.

Amy Sayle is Morehead's Science 360 project manager. She's considering setting her alarm clock for 6:30 a.m. to see Mercury.

Io passing in front of  Jupiter. (Credit: Cassini Imaging Team, Cassini Project, NASA)

Io passing in front of Jupiter. (Credit: Cassini Imaging Team, Cassini Project, NASA)

In the Science 360 program “Bring the Universe to Light,” MPSC educators tell the story of Galileo Galilei’s surprising observations of the planet Jupiter.

With a telescope or even just a decent pair of binoculars, you can discover what Galileo did 400 years ago: Jupiter has moons that orbit it. This observation contradicted a commonly held view that everything revolved around Earth.

Tonight, something special happens with these dancing points of light that Galileo observed. Two moons, Ganymede and Europa, will appear to cast dark shadows on Jupiter as they pass in front of the planet. And Io will disappear as it passes behind.

The Chapel Hill Astronomical and Observational Society invites the public to join them for an informal telescope viewing of this moon dance after 9 p.m. tonight, Wednesday, Aug. 26, at Farrington Point, Jordan Lake. (Please note this is not the same place where the regular Morehead skywatching sessions meet.)

Amy Sayle is Morehead's Science 360 manager.

Moonlight (and possibly clouds) will interfere with early morning viewing of the 2009 Perseid meteor shower.

The annual Perseid meteor shower peaks this Wednesday (August 12).

Last year I recommended going out to view the Perseids at the ridiculous hour of 4 a.m. I vividly remember both the many meteors I saw between 4 and 5 a.m., as well as the effort involved in staying awake at work in the hours that followed.

This year, you and I can justify not trying so hard for two reasons:

(1) The weather. The forecast doesn’t look terribly clear for the Triangle.

(2) The Moon. After about 11 p.m., moonlight will wash out the dimmer meteors from view. The almost last quarter Moon rises within a few hours after sunset and stays up the rest of the night.

Meteors are also known as “shooting stars,” but they’re not related to stars. Meteors are caused when Earth travels through space debris (that left by Comet Swift-Tuttle in the case of the Perseids). When the debris interacts with the Earth’s atmosphere, a flash of light is created.

Perseid meteors appear to radiate away from the constellation Perseus, but you don’t need to know how to find Perseus to see the meteors. Take a lawn chair or sleeping bag to a spot away from city lights, and look about halfway up the sky. Choose a direction that’s dark.

If skies are clear, the best times to look for Perseid meteors include Tuesday evening to Wednesday before dawn, and Wednesday evening to Thursday before dawn. The most activity will be between midnight and dawn. If you’re watching after the Moon has risen, look away from it to a darker part of the sky. After giving your eyes 15 minutes or more to adjust to the darkness, you may see a Perseid meteor every few minutes.

If the weather permits, Morehead will hold a special Perseids skywatching session from 9 to 11 p.m. this Wednesday, Aug. 12, at Jordan Lake (Ebenezer Church Recreation Area).

Amy Sayle is Morehead's Science 360 manager.


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