Lecture 02

Namaskar. So, welcome back. We had stopped this discussion here. We were talking about the planet. Why is the planet so important? Because it supports life. And there is no planet yet in which such life has been supported and such life has been found elsewhere. So, this is why we say that the earth is unique in its sense in terms of the chemical and physical mix. And secondly, such life does not exist elsewhere because the environment there does not support it. Now, if we look at the large solar system, then the solar system is divided into three parts. So, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. So, we call them Juvian. So, what is the difference between Juvian planets and terrestrial planets? Terrestrial planets are rocky planets and Juvian planets are mainly your gaseous giant. So, earth can be divided into two groups and one is your terrestrial planets which are Mercury, Venus, Earth, Mars which is closest to the sun. And small rocky and dense characteristics of terrestrial planets are that they are small, rocky and dense. So, so farther from the sun than Mars, the earth is much larger than the terrestrial. So, now some facts of the earth. So, the earth is 30% landmass and 70% oceans. So, the earth is 30% landmass and 70% oceans. So, the earth is 30% landmass and 70% oceans. So, the earth is 30% landmass and 70% oceans. So, geological processes. So, geological processes. So, over a million of years layer sediments built up over that rock. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, the earth is a dynamic planet. So, different layers are formed. The composition is different, the temperature is different, the pressure is different, some parts are liquid, some are solid. Why this happened, we will discuss later. But, initially the planet was cold the composition was uniform the impact transferred the kinetic energy transfer the kinetic energy evaporation So, these four systems make the Earth complete. Here is the biosphere, geosphere, hydrosphere, which is related to water, and atmosphere, which is at the upper level. The second point is that energy and material like water, carbon and minerals are transferred from one system to another system. Within Earth, and as Earth as a whole system, if we talk about the whole system, there is an exchange. They interact with each other. You can see here, there is an exchange. For example, if we talk about the hydrosphere, the water from here goes up in the form of water vapour, then comes down in the form of clouds, and then comes back. This cycle is going on. On this basis, if we take these systems, to a close approximation, Earth is a closed system, but not fully, because as we said, there is a meteorite impact, but it is very less, not very much, so we see it as a closed system. As we said, an open system can exchange both energy and matter across its boundary, and this is within Earth's system. As I said, there is an exchange. This is an example of an open system, because in this, both things are exchanging. Sunlight energy is also exchanging, and matter across the boundaries. The drainage basins are the internal open system. Internally, we have an open system, but overall, the approximation, approximately, Earth is a closed system. We have already discussed this. We will stop here, and in the next lecture, we will discuss in more detail. Goodbye!