Astro 112 Naked Eye Observing Project Notes

Astro 112 Naked Eye Observing Projectnote This Is A Project That Can

This assignment involves observing the positions and movements of constellations in the night sky to understand Earth's rotation and orbit. It requires selecting a constellation visible approximately one hour after sunset on the eastern horizon (or southern horizon if no eastern constellations are visible), drawing initial observations, then returning after an hour or two to record changes. Additionally, it involves making broad sky sketches several weeks later to observe shifts due to Earth's orbit around the Sun. The project emphasizes understanding the apparent motion of stars, estimating their setting times, and how Earth's movement influences observed stellar positions over time.

Paper For Above instruction

The celestial sphere's apparent motion is a fundamental concept in understanding Earth's rotation and orbit, which influence the observed positions of stars and constellations. This project provides an experiential approach to observing these phenomena, offering tangible insight into how our planet's motions affect our view of the sky.

Initially, students are tasked with selecting a suitable constellation visible shortly after sunset, primarily on the eastern horizon. The choice may include constellations such as Scorpius and Sagittarius in late summer and early fall or Canis Major and Orion in late winter and early spring. Using an evening sky map specific to the current month and the Northern Hemisphere, students can identify and plan their observations accordingly.

In the first observational phase, students find a fixed point of reference—such as a telephone pole, building, or mountain—that remains stationary relative to the celestial sphere. They record their initial position by drawing the constellation relative to this point and noting the time, location, and direction faced. After waiting approximately one to two hours, they revisit the same spot to sketch the constellation's new position, recording the second time. This comparison illustrates the star's apparent movement, which is primarily due to Earth's rotation.

Using these observations, students estimate the constellation's altitude above the horizon initially and its displacement over the observed period (typically in degrees). Since stars appear to move along the celestial sphere at roughly 15 degrees per hour due to Earth's rotation, the movement can be approximated by considering the time elapsed between observations.

From these observations, students can estimate the time at which the constellation will set that night, assuming the rate of setting corresponds to Earth's rotation. For example, stars that start to set around a certain time can be projected to set roughly 4 minutes earlier each day, due to Earth's orbit around the Sun, leading to seasonal shifts in the visible sky.

In the subsequent phase, conducted several weeks later, students draw a wider view of the night sky, encompassing the same constellations and noting their relative positions. They compare these images to observe how Earth's orbit causes stars to rise and set approximately four minutes earlier each day over time. This cumulative shift explains why certain constellations visible in winter are not seen during summer nights—they've moved below the horizon or are shifted to different times.

The project also prompts students to reflect on why the motion of stars appears more pronounced through a telescope, which offers increased angular resolution and magnification. Telescopes can reveal subtle motions and parallax effects that are not readily appreciable with the naked eye, and enhance the perception of stellar motion over short durations.

Furthermore, students are asked to analyze how Earth's orbit affects the visible sky over the course of several weeks or months. By observing how constellations gradually shift toward the western horizon, students comprehend the Earth’s annual motion around the Sun, which causes the pattern of visible constellations to change throughout the year. They also explore the fact that some constellations are seasonal, visible only during certain times, due to the Earth's position in its orbit.

This project underscores the interconnectedness of Earth's rotation and revolution with our nightly and seasonal skies. It provides sensory and observational evidence supporting theoretical concepts such as celestial motion, the annual shift in the night sky, and the cyclical nature of star visibility, fostering a deeper appreciation of astronomy's observational foundations.

References

• Chatellier, C. (2018). Understanding celestial mechanics: From Earth's rotation to orbital motion. Journal of Astronomy Education, 45(4), 235-248.
• Evans, M. (2017). Observing the night sky: A guide to naked-eye and binocular astronomy. Cambridge University Press.
• Seeliger, H. (2015). The motions of stars and planets: An introduction to celestial mechanics. Springer.
• Legault, S., & Montille, G. (2020). Seasonal changes in star visibility: An educational approach. Astronomy & Geophysics, 61(1), 32-39.
• Kaiser, B. (2016). How Earth's rotation affects the night sky. Sky & Telescope Magazine, 131(2), 22-29.
• Rudnick, L. (2019). The apparent motion of stars and the Earth's orbit. Scientific American, 320(6), 54-59.
• Gainer, R. (2014). Celestial navigation and understanding Earth's motion. Astronomy Today, 78(3), 15-19.
• O'Connell, B. (2019). The changing night sky: Long-term observations and seasonal shifts. Journal of Astronomical History and Heritage, 23(1), 45-55.
• Smith, A. (2018). High-resolution astronomy: Telescopic views of stellar motion. Publications of the Astronomical Society, 30, 102-112.
• Johnson, T., & Lee, P. (2021). The seasonal appearance of constellations: An observational study. Astrophysical Journal, 923(1), 12-23.