Access the Seasons and Ecliptic Simulator from the Basic Coordinates and Seasons section of the NAAP Labs Application. 2. Click reset, select the celestial sphere view, and turn on labels in the main window. 3. You’ll notice the Sun’s declination (6) and right ascension (a) are indicated in the lower left corner of this window. You’re going to use this information to make four equally spaced stops along the celestial equator. These are four critically important locations and you’ll need to figure out why. 4. To complete the following data table, begin by dragging the Sun around the celestial sphere (or starting and stopping the animation) until you reach the declination and right ascension measurements indicated. Make sure to enter dates as they appear in the simulator (day first), and Vernal Equinox, Summer Solstice, Autumnal Equinox, or Winter Solstice for the special name (spelling counts). a (h) 0.0 6.0 12.0 18.0 24.0 8 (degrees) 0.0 23.4 0.0 -23.4 -0.2 Special name *0.0 and 24.0 actually reference the same point and will likely appear as 23.9 in the simulation. These numbers are specified here to make sure you see how a full cycle has occurred. Similarly, the 8 of -0.2 should be a perfect 0.0 at the moment the Sun has completed one full cycle. Date
The Correct Answer and Explanation is :
The four key positions of the Sun along the celestial equator correspond to the equinoxes and solstices, marking the transitions between the seasons. Here’s a summary of these positions:
| Right Ascension (h) | Declination (°) | Special Name | Approximate Date |
|---|---|---|---|
| 0.0 | 0.0 | Vernal Equinox | 20 March |
| 6.0 | +23.4 | Summer Solstice | 21 June |
| 12.0 | 0.0 | Autumnal Equinox | 23 September |
| 18.0 | -23.4 | Winter Solstice | 21 December |
| 24.0 (or 0.0) | 0.0 | Vernal Equinox | 20 March |
Explanation:
The Sun’s apparent movement along the celestial sphere is a result of Earth’s axial tilt and its orbit around the Sun. This movement is tracked using two celestial coordinates:
- Right Ascension (RA): Analogous to terrestrial longitude, RA measures the Sun’s position eastward along the celestial equator, expressed in hours (0 to 24h).
- Declination (Dec): Similar to latitude, declination measures the Sun’s angular distance north or south of the celestial equator, expressed in degrees.
The equinoxes and solstices are defined by specific combinations of RA and declination:
- Vernal Equinox (RA: 0h, Dec: 0°): Around 20 March, the Sun crosses the celestial equator moving northward. Day and night are approximately equal in length.
- Summer Solstice (RA: 6h, Dec: +23.4°): Around 21 June, the Sun reaches its northernmost point, resulting in the longest day of the year in the Northern Hemisphere.
- Autumnal Equinox (RA: 12h, Dec: 0°): Around 23 September, the Sun crosses the celestial equator moving southward, leading to nearly equal day and night durations.
- Winter Solstice (RA: 18h, Dec: -23.4°): Around 21 December, the Sun reaches its southernmost point, resulting in the shortest day of the year in the Northern Hemisphere.
These positions are critical for understanding the changing seasons, as they directly influence the amount of sunlight different parts of Earth receive throughout the year.