Use the Starry Night Enthusiast \(\mathrm{TM}^{\mathrm{M}}\) program to observe the Milky Way. (a) Display the entire celestial sphere by selecting Favourites \(>\) Guides \(>\) Atlas. Select View \(>\) Stars \(>\) Milky Way to display this galaxy. Select Options \(>\) Stars \(>\) Milky Way, move the Brightness slide-bar to the far right to brighten the Milky Way and click OK. In the View menu, ensure that the Scrollbars are activated and use them to look at different parts of the Milky Way. Can you identify the direction toward the galactic nucleus? In this direction the Milky Way appears broadest. Open the Find pane, enter Sagittarius in the Query box and press Enter to center on this constellation to check your identification. (b) Use this full-sky view to determine the orientation of the plane of the Galaxy with respect to the celestial sphere. Move the vertical scrollbar to its central position to display the Celestial Equator as a horizontal line across the lower part of the view. Move the horizontal scrollbar until the Milky Way is centered upon the view. Estimate the angle between the Milky Way and the celestial equator on the screen. How well aligned is the plane of the Milky Way with the plane of the Earth's equator? (c) A third plane of interest is that of the ecliptic, which is shown as a green line. Use the scrollbars to adjust the view so that the ecliptic appears as a straight line rather than as a curve, thereby ensuring that you are viewing in a direction that lies in the ecliptic plane. Use the horizontal scrollbar to move the view to where you can see where the ecliptic crosses the Milky Way. Estimate the angle between the Milky Way and the ecliptic on the screen. How well aligned is the plane of the Milky Way to the ecliptic, the plane of the Earth's orbit around the Sun? (d) Click on Home in the toolbar to return to your home view, stop Time Flow and set the local time to midnight (12:00:00 A.M.). Select Options > Stars > Milky Way, move the Brightness slide-bar to the far right to brighten the Milky Way and click OK. Adjust the date to January 1, then February 1, and so on. In which month is the galactic nucleus highest in the sky at midnight, so that it is most easily seen from your location?

Step by step solution

01

Display the Milky Way using Starry Night

Open the Starry Night Enthusiast program. Follow the path Favourites > Guides > Atlas to display the entire celestial sphere. Then, select View > Stars > Milky Way to display the Milky Way. Increase the brightness of the Milky Way by going to Options > Stars > Milky Way and moving the Brightness slide-bar to the far right.

02

Identify the Galactic Nucleus

Use the activated Scrollbars in the view menu to look at different parts of the Milky Way. Try to identify the direction towards the galactic nucleus. The Milky Way appears broadest in this direction. To check your identification, open the Find pane, enter 'Sagittarius' in the query box and press enter. This will center the view on the Sagittarius constellation.

03

Determine the Alignment of the Milky Way with the Earth’s Equator

Use the scrollbars to centralize the vertical scrollbar position which will display the Celestial Equator as a horizontal line across the lower part of the view. Move the horizontal scrollbar until the Milky Way is centered upon the view. Now, estimate the angle between the Milky Way and the celestial equator. This will help you understand how well aligned the Milky Way is with the plane of the Earth's equator.

04

Determine the Alignment of the Milky Way with the Plane of the Ecliptic

Adjust the view so that the ecliptic appears as a straight line rather than as a curve, indicating that the view is in a direction that lies in the ecliptic plane. Move the view to where you can see where the ecliptic crosses the Milky Way. Estimate the angle between the two. This will give an idea of the alignment of the Milky Way to the ecliptic.

05

Observe the Position of the Galactic Nucleus during Different Months

Return to your home view by clicking on 'Home'. Stop Time Flow and set the local time to midnight. Brighten the Milky Way as described in Step 1. Adjust the date to January 1, then change the date monthly to February 1, March 1, and so on. Observe in which month the galactic nucleus is highest in the sky at midnight. This will help determine when it is most visible from your location.

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Key Concepts

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

Milky Way Observation

Observing the Milky Way is a captivating experience that allows us to look directly into our home galaxy. The Milky Way can be seen as a faint band of light that stretches across the sky when viewing conditions are optimal. For stargazers and astronomers using software programs like Starry Night Enthusiast ^TM, visualizing the galaxy becomes an interactive exercise.

When observing the Milky Way, identifying the galactic nucleus is a key task. It is the bulging center of the galaxy and can be located by finding the constellation Sagittarius. This region appears broader and denser with stars, marking the heart of the Milky Way. With increased brightness settings, the Milky Way's structure, including its spiral arms, becomes more discernible. It's during the absence of moonlight and away from city lights that the Milky Way reveals its true splendor, providing an awe-inspiring glance into the vastness of our galaxy.

Students are usually instructed to observe and estimate the degree to which the Milky Way’s band aligns with other known celestial guides, which helps to understand the galaxy's orientation in space. The location of Sagittarius and the appearance of the Milky Way's nucleus change over the course of the year, indicating that our view from Earth is constantly in motion. This is a pivotal concept in astronomy and aids in comprehending the dynamic nature of the cosmos.

Celestial Equator

The celestial equator is an imaginary line that extends Earth's equator into the sky. It serves as a basis for the equatorial coordinate system, one of the most commonly used celestial coordinate systems. Understanding the celestial equator helps observers on Earth determine how celestial bodies move and appear to us throughout the year.

In astronomical software or during stargazing, the celestial equator can be envisioned or sometimes displayed as a straight line parallel to our Earth's equator, dividing the sky into northern and southern hemispheres. The angle between the celestial equator and the Milky Way provides insight into how our solar system is oriented with respect to the rest of the galaxy. For instance, the Milky Way is not perfectly aligned with our celestial equator, explaining why it extends across the sky at an angle rather than running straight from east to west.

The significance of understanding the celestial equator extends to comprehending daily and annual motions of celestial objects. Because our planet's axis is tilted with respect to its orbit around the Sun, the celestial equator is tilted in relation to other important celestial markers, like the ecliptic plane, which is vital for learning the basics of celestial navigation and understanding astronomical phenomena such as the seasons and the zodiac.

Ecliptic Plane

The ecliptic plane is another fundamental concept in astronomy, directly related to Earth’s orbit around the Sun. It represents the plane of Earth's orbit, extended out into space. When we talk about the ecliptic plane, we are essentially considering the sun's apparent path across the sky over the year.

In practice, the ecliptic is marked by the zodiac constellations. Observatories and planetarium software may show the ecliptic as a line - often green - weaving through these constellations. The angle between the Milky Way and the ecliptic is of particular interest because it tells us about the orientation of our Solar System within the galaxy. Usually, the Milky Way and the ecliptic cross at roughly a 60-degree angle, highlighting the fact that our planetary system is tilted with respect to our galaxy's overall structure.

Understanding the ecliptic plane is crucial for comprehending events like eclipses and planetary transits. It is through this plane that astronomers can predict the positions of the sun, moon, and planets, and it is a reference point for space missions when charting paths for probes and telescopes. Encountering the ecliptic in this context provides students with a better understanding of the third-dimensional aspect of astronomy and the alignment of celestial bodies.