• Vinita Domier

Take a Closer Look at the Moon

Updated: Oct 16, 2021

logo: International Observe the Moon Night. Outline of a man and boy looking through a telescope in front of the moon
International Observe the Moon Night

By Vinita Domier

NASA Solar System Ambassador

Join the Davis Astronomy Club on Saturday, October 16, starting at 7:00pm in front of the Explorit Science Center (3141 5th Street, Davis) for a special meeting to participate in NASA’s annual International Observe the Moon Night. All ages are invited to the free outdoor meeting and star party where we will observe the Moon, planets, and stars. Mask wearing is highly recommended.

International Observe the Moon Night reminds us to appreciate the beauty, grandeur, and importance of Earth’s sole satellite. The event is held on the Saturday closest to the first first-quarter phase of the Moon in the fall, when the Moon is ideal for evening observing as it is overhead at sunset and sets around midnight. More information about the event and moon activities can be found at the following link: https://moon.nasa.gov/observe-the-moon-night/

After the Sun, our Moon is the most prominent and brightest object in the sky. The Moon is 27% (about one quarter) of the size of the Earth, and it revolves around the Earth in an elliptical orbit at an average distance of a mere 240,000 miles, thereby making it our closest neighbor. As the Moon is smaller and 60% less dense than Earth, the gravitation force on the Moon’ surface is 16.6% (about one-sixth) of the Earth’s surface gravity.

Unlike the Sun which shines due to the electromagnetic radiation produced by nuclear fusion in its core, the Moon is visible only by reflecting the Sun’s light. While half of the Moon is always bathed in sunlight while the other half is plunged in shadow, observers on Earth see different parts of the Moon illuminated as it orbits around Earth. The changing shapes of the sunlit portions of the Moon are known as its phases and it goes through a complete cycle, as seen from Earth (its synodic period), in 29.5 days.

Because of synchronous rotation, the Moon takes 27.3 days to rotate on its axis and the same time to revolve around the Earth as seen against the background stars (its sidereal period). This results in the same half (near side) always facing Earth and the other half (far side) never visible from Earth. The Moon has an extremely rarified atmosphere with no wind or water on the surface to cause any appreciable erosion, and has extreme daytime and nighttime temperature swings from +260°F to -280°F.

The evening of October 16, the Moon (in Aquarius constellation) will be in between the first quarter and full moon phase. We will observe the Moon’s numerous stark meteor craters, whitish highlands, and flat greyish solidified lava ‘seas’ using telescopes and binoculars, especially around the terminator line which delineates the lit and unlit parts of the Moon. We will also observe planets close to the Moon in the southern sky (in Capricornus constellation) – very bright Jupiter (visual magnitude -2.5) and semi-bright Saturn (visual magnitude (+0.6). Super bright Venus (visual magnitude -4.2 in Scorpius constellation) will be low in the western horizon.

International Observe the Moon Night with the Davis Astronomy Club is Saturday, October 16 at Explorit Science Center (3141 5th Street, Davis), beginning at 7:00pm. For more information, please contact Vinita Domier at vcdomier@yahoo.com.


Explorit's coming events:

· Come explore our exhibit Healthy Planet, Healthy You during our Public Hours: Friday 1-4pm, Saturday and Sundays 10am-2pm. Admission is $5 per person, free for Members, ASTC, and those aged 2 and under. Reserve a timed entry at https://www.explorit.org/events.

· Like many small businesses the closures have had a significant impact on our income and sustainability. Now is a great time to donate and help Explorit continue to educate and inspire the scientists of tomorrow: https://www.explorit.org/donate.

· Continue to support Explorit during this uncertain time by becoming a member. An Exploit Membership not only support us but grants the recipient with free visits to Explorit’s regular public hours, discounts on events, summer and after-school camps, and workshops, and gives you ASTC benefits to visit other museums throughout the world. For more information visit https://www.explorit.org/membership or call Explorit at 530-756-0191.