(1) Representing a Sphere on a Map; (2)Solstices and Equinox and (3) The midnight sun
Representing a sphere like the Earth on a flat map is a challenging task because it requires transforming a three-dimensional object into a two-dimensional surface. Here are three main ways to do this:
1. Cylindrical Projection
- How it works: Imagine wrapping a cylinder around the Earth. The Earth’s surface is projected onto this cylinder, which is then unwrapped to create a flat map. This method is commonly used for navigation because it keeps straight lines straight, making it useful for sailors and pilots.
- Examples: Mercator and Gall-Peters projections are well-known cylindrical projections.
- Pros and Cons: It’s great for navigation but can distort sizes and shapes, especially near the poles.
2. Conical Projection
- How it works: This method involves projecting the Earth’s surface onto a cone. The cone is then cut along a meridian and flattened to create a map. It’s useful for mapping smaller regions.
- Examples: Often used for road and weather maps.
- Pros and Cons: Good for east-west orientations but distorts more as you move away from the standard parallel.
3. Azimuthal Projection
- How it works: This method projects the Earth onto a flat surface from a single point, like the North Pole. It’s useful for showing areas around a central point.
- Examples: Gnomonic projection is a type of azimuthal projection.
- Pros and Cons: Great for showing shortest distances and angles from a central point but distorts shapes and sizes away from the center.
EQUINOXES AND SOLSTICES
Equinoxes
- Occur twice a year, around March 20 and September 22
- Day and night are almost equal in length worldwide
- The Sun shines directly on the Earth’s equator13
Solstices
- Happen twice a year, around June 21 and December 21
- Mark the longest and shortest days of the year
- Summer solstice: longest day, shortest night
- Winter solstice: shortest day, longest night13
These events cause our seasons to change and affect things like weather and how long our days are1.
