What is the "greenhouse effect"?
To answer this question, we first need to clarify what a greenhouse gas is considered as. To put it simply, a greenhouse gas is a gas that can "hold in heat". Examples of these gases include but are not limited to Carbon Dioxide, Methane, and water vapor. Now that the definition of the a greenhouse gas has been established, we can continue. The Earth orbits around the sun, so the Earth experiences solar radiation and is heated up because of this. Incoming solar radiation comes through the Earth's atmosphere in short wavelengths and strikes the Earth's surface. Once the Earth is heated from the incoming solar radiation, heat is then radiated off the Earth's surface by longer wavelength infrared radiation. The greenhouse gases in the atmosphere allow the short wavelength solar radiation to come through, but they DO NOT let the infrared radiation pass through and leave the atmosphere. this then locks in the infrared radiation from the Earth's surface in the atmosphere and greatly contributes to warming of the Earth.
What causes seasons on Earth?
To the surprise of many, the "reason for the seasons" is NOT because of the Earth's orbit around the sun. The orbit plays an important role in the seasons because of the elliptical shape of the orbit or the Earth around the sun so at some points in the orbit the Earth is either closer to the sun or further away from it; but this is not the main factor that creates the seasons. This main factor is the fact that the Earth spins on an axis that is tilted about 23 degrees off the vertical. This tilt allows the northern hemisphere to be closer to the sun at points in the orbital year compared to the southern hemisphere, as well as further away from the sun compared to the southern hemisphere. For example, during the northern hemisphere's summer, the north pole is tilted TOWARDS the sun. This increases the incoming solar radiation to this portion of the Earth and allows for higher temperatures, creating summer. On the other hand, while this is happening, the southern hemisphere is tilted AWAY from the sun and this is the winter for the southern hemisphere. Being tilted away decreases the solar radiation and thus decreases temperatures and allows winter. This tilt is what is the "reason for the seasons".
What is the origin of the solar system and how can this be proven?
The origin of the solar system has been discussed for generations, yielding many theories and explanations from biblical origins to more scientific origins. A theory that has been heavily researched with concrete evidence to support it is known as the Solar Nebular Theory. This theory suggests that a supernova event, otherwise known as an "exploding star" expelled matter into open space from an ancient, previously active star. Over millions of years, this matter concentrated due to gravitational attractions between said matter, and eventually formed a Nebular Cloud. This cloud continued to spiral due to gravity and soon formed what is know as our sun rich in Hydrogen and Helium. Once this massive star was created, it had great gravitational attraction to surrounding matter that was left over from the previously mentioned supernova event as well as new ones that happened after the sun's creation. This collection of matter continued to circle around the sun and coalesce with surrounding matter due to gravity to form planetary bodies that orbit the sun. Evidence that can be used to support this theory includes the fact that all of the planets that orbit the sun are on the same orbital plane. This plane is a disk like pattern which hints towards a spiraling pattern of collection of matter. Also, all the planetary bodies orbit the sun in the same direction which also hints towards the spiral formation motion previously mentioned above.