NEXT STOP: EARTH!
Imagine a blank sphere floating in the middle of space. Now picture the whole sphere flooded by blue oceans, rivers, and lakes. And seven continents, defined by low elevation green patches, high elevation brown areas, and deserts golden brown. Add white ice caps capping the North and South Poles. And white swirling clouds in the atmosphere. Then tilt the whole sphere 23.5 degrees. There. Our home planet, Earth!
Third planet from the Sun and the only planet to support life, Earth, or the Blue Planet, formed 4.54 billion years ago from accretion of the solar nebula and first hosted life approximately 1 billion years ago. Though technically not named after any Gods, the Greek god Gaea is mother of the earth. Home to millions of species, Earth has the “Goldilocks Phenomenon” since all conditions including climate and temperature support life. Earth is in the “life zone,” where water exists in all three phases: gas, liquid, and solid. Earth’s surface is 30% land and 70% water. Collectively, the biosphere and the abundance of minerals support life. Earth’s atmosphere, specifically the ozone layer, and magnetic field blocks high-energy electromagnetic radiation harmful for life. The axis of the Blue Marble, the largest terrestrial planet, tilts 23.5 degrees, causing the four annual seasons. The hemisphere tilting toward the Sun is in summer and the other is in winter. In fact, Earth’s orbit is nearly circular and Earth is actually closer to the Sun in winter than in summer. Earth’s tectonic activity, or the sliding of tectonic plates, causes volcanic activity and earthquakes that renew Earth’s surface. A viscous liquid mantle and a rigid crust surround a solid core. Earth orbits the Sun once every 365.25 days and rotates once every 24 hours. Earth has one moon, or natural satellite.
Earth only has one moon, called the Moon. Reflecting sun light, this natural satellite orbits the Earth once every ~29 days, seen in different phases throughout every month: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent. Formed about 4.53 billion years ago, the Moon is an imperfect sphere bombarded by asteroids and comets during the Late Bombardment Period 3.8-4.1 billion years ago. In fact, the Near Side is much smoother than the Far Side (never observed from Earth), so one theory is that the Moon was actually two chunks of material that collided. However, the giant impact hypothesis indicates that a large object collided into Earth’s surface and while some mass fused with Earth, the rest formed the Moon. This theory explains why the Moon’s interior is similar to that of Earth. The Moon’s gravitational pull contributes the movement of ocean tides, stabilizes Earth’s tilt, and gradually slows the Earth’s rotation.
- Order in Solar System: #3
- Number of Moons: 1
- Orbital Period: 1 year
- Rotational Period: 1 day
- Mass: 2.9736 x 10^24 kg
- Volume: 1.08321 x 10^12 km³
- Radius: 6,371 km
- Surface Area: 5.10 x 10^8 km²
- Density: 5.515 g/cm
- Surface Pressure: 101.325 kPa
- Eccentricity of Orbit: 0.0167
- Surface Temperature (Average): 287.2 K
- Escape Velocity: 11.186 km/s
- Apparent Magnitude: N/A