Exploring Our Solar System

• Stars in our solar system: There is only one star in our solar system, which is the Sun.

• Shape of our orbit: The shape of our orbit around the Sun is elliptical.

• Kepler's 3 Laws:

  1. Planets move in elliptical orbits with the Sun at one focus.

  2. The line connecting a planet to the Sun sweeps out equal areas in equal times.

  3. The square of a planet's orbital period is proportional to the cube of its average distance from the Sun.

• Rotation: Earth completes 1 full rotation on its axis in a sidereal day (23 hours, 56 minutes, and 4 seconds).

• Revolution: Earth completes 1 full revolution around the Sun in a year.

Our Orbit:

Trivia: Did you know that the shape of our orbit around the Sun is elliptical? This means that our path is not a perfect circle, but rather an elongated oval. It takes us closer to the Sun at one point (perihelion) and farther away at another point (aphelion). Our elliptical orbit is what causes the changing seasons on Earth!

Effects of Earth's Tilt

• Earth's axis is tilted at 23.5°
• Axis remains fixed in space
• Summer: Northern hemisphere tilted towards the Sun
• Winter: Northern hemisphere tilted away from the Sun
• Higher altitude of the Sun in summer

Higher Altitude in Summer

In summer, the Northern hemisphere is tilted towards the Sun, causing it to be higher in the sky. This results in longer days and shorter nights. The Earth's axis is tilted at 23.5°, which affects the angle at which sunlight reaches different parts of the planet.

Trivia:

• Longer days: The higher altitude of the Sun in summer leads to more daylight hours.
• Seasonal changes: The tilt of the Earth's axis causes the changing seasons.
• Winter contrast: In winter, the Northern hemisphere is tilted away from the Sun, resulting in lower altitudes and shorter days.

The Reason for Seasons

The Earth's tilted axis causes the seasons. The amount of direct sunlight determines the season. During the summer solstice, the Sun is directly overhead at the Tropic of Cancer (23.5° N), resulting in the Sun's maximum altitude in the northern hemisphere. The winter solstice occurs when the Sun is directly overhead at the Tropic of Capricorn (23.5° S).

Seasons on Earth

The Earth's tilted axis is the main cause of the seasons. As the Earth orbits the Sun, different parts of the planet receive varying amounts of sunlight. This creates the four seasons: spring, summer, autumn, and winter. During the winter solstice, the Sun's maximum altitude in the northern hemisphere is at its lowest, resulting in shorter days and colder temperatures.

Equinoxes

• Equinoxes: When the Sun is directly overhead at the equator, both hemispheres receive equal amounts of sunlight.

• Autumnal Equinox: Occurs around September 21, halfway between the summer and winter solstices.

• Vernal Equinox: Occurs around March 21, halfway between the winter and summer solstices.

• Tropic of Cancer/Capricorn: Sun is 23.5° from the point directly overhead during the equinoxes.

• Observer at 23.5º N: Sun's positions on winter solstice, vernal equinox, and summer solstice. Same altitude on autumnal equinox as vernal equinox.

Equinoxes:

• They result in equal amounts of sunlight in both hemispheres.
• Equinoxes mark the halfway point between the summer and winter solstices.
• They occur when the Sun is directly overhead at the equator.
• Equinoxes are observed on September 21 and March 21.