Use the Starry Night Enthusiast \({ }^{\mathrm{TM}}\) program to observe the changing appearance of the Moon. Display the entire celestial sphere by selecting Guides \(>\) Atlas in the Favourites menu. Open the Find pane by clicking the Find tab at the top of the left border of the view window. Click the menu button (the blue colored button with a downward- pointing arrowhead) at the left of the entry in the list for the Moon and select the Magnify option. This will center a magnified image of the Moon in the view as seen from the center of a transparent Earth. Close the Find pane by clicking its tab. Click on the down arrow to the right of the Time Flow Rate control and select hours from the drop-down menu. Then click on the Run Time Forward button (a triangle that points to the right like a Play button). (a) Describe how the phase of the Moon changes over time. (b) Look carefully at features near the left-hand and righthand limbs (edges) of the Moon. Are these features always at the same position relative to the limb? Explain in terms of libration.

Step by step solution

01

Launch Starry Night Enthusiast TM

Navigate to Starry Night Enthusiast TM and open the program.

02

Open Guides > Atlas

Once in the program, select Guides \(>\) Atlas from the Favourites menu to display the entire celestial sphere.

03

Open Find tab and select Moon

Open the Find pane by clicking the Find tab at the top of the left border of the view window. Click the menu button (the blue colored button with a downward-pointing arrowhead)at the left of the entry in the list for the Moon.

04

Magnify Moon's image

From the dropdown menu of the Moon, select the Magnify option. This action will center a magnified image of the Moon in the view as seen from the center of a transparent Earth.

05

Close Find pane

Close the Find pane to clear the view by clicking its tab.

06

Set Time Flow Rate control to hours

Navigate to Time Flow Rate control and click the down arrow to bring about a drop-down menu. Then, select 'hours' from this list.

07

Initiate time lapse

To initiate a time lapse, click on the Run Time Forward button, which is represented by a triangle that points to the right.

08

Observation - Changes in the Moon's phase

Observe the changes in the phase of the Moon over the hours. Take note of the different shapes and how they change over time.

09

Observation - Lunar features and libration

Pay attention to the features near the Moon's left-hand and right-hand edges. See if these features maintain their same position relative to the limb. Explain any changes observed in terms of libration, the slight oscillation in the Moon's orientation which allows us to see a little more than half of its surface over time.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Moon Phases

The phases of the Moon are a captivating celestial phenomenon that occurs due to the changing positions of the Moon, Earth, and Sun. Over the course of roughly a month, we witness a cycle starting from a New Moon, when the Moon is aligned between Earth and Sun, to a Full Moon, and back again. As the Moon orbits Earth, sunlight illuminates different fractions of the side facing us, creating the phases.

The phases proceed as follows: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Last Quarter, and Waning Crescent. During the waxing phases, the right side of the Moon (as perceived in the Northern Hemisphere) becomes increasingly illuminated, reaching full brightness during the Full Moon. Conversely, during the waning phases, the illumination decreases from the right side, leading up to the New Moon. The Starry Night Enthusiast software enables users to visualize this process in an accelerated time-lapse, enhancing understanding of the Moon's changes visible from Earth.

Libration

Libration is an apparent oscillating motion of the Moon that allows observers on Earth to see slightly more than half of the lunar surface over time. It is caused by the combination of the Moon's elliptical orbit, its axial tilt, and the gravitational interactions with Earth.

Types of Libration

There are several types of libration, including:

• Libration in Longitude: As the Moon's orbital speed varies due to its elliptical path, this form of libration lets us peek at a bit more of the Moon's eastern or western edge at different times.
• Libration in Latitude: Due to the Moon's tilted axis in relation to its orbit around Earth, we can sometimes catch glimpses above and below the average limits of the Moon's poles.
• Diurnal Libration: Because of Earth's rotation, observers can see slightly around the edge of the Moon at moonrise and moonset compared to when it is overhead.

Using the Starry Night software, students can observe this effect by paying attention to the features near the Moon's limbs, noting that they shift in position relative to the limb over time.

Starry Night Enthusiast Software

Starry Night Enthusiast is a powerful and user-friendly software designed for astronomical observations and education. With this virtual planetarium, students and enthusiasts can simulate the night sky from any location on Earth, at any time and date, with a realistic 3D visual.

The software offers a range of features to enhance learning and exploration, such as the ability to magnify celestial objects for detailed viewing, time lapse controls to observe motions and changes over time, and a comprehensive celestial database. Through Starry Night, users can observe lunar phases, planetary movements, and other astronomical events as they unfold in stunning detail, making complex concepts more accessible to learners of all levels.

Celestial Sphere Observation

Observing the celestial sphere is fundamental in understanding the positions and movements of celestial objects as seen from Earth. The celestial sphere is an imaginary sphere with Earth at its center, on which all astronomical objects are thought to lie.

Key reference points on the celestial sphere include the celestial poles, celestial equator, ecliptic, and coordinate grids which help in locating objects in the sky. When using software like Starry Night Enthusiast, students can visualize these components and grasp how they change with time and from different geographic locations. Additionally, observers can experience the apparent daily rotation of the celestial sphere, which is actually due to Earth's rotation, and seasonal changes explained by Earth's orbit around the Sun. Tools like Starry Night turn these abstract concepts into interactive, observable phenomena, reinforcing learning through virtual celestial observation.