planets

• Uranus is the coldest planet in our Solar System.
• The historical development of theories that explain the origin of the Universe has been described.
• Theories that explain the origin of the universe have been differentiated.
• Different hypotheses explaining the origin of the Solar System have been compared.
• Other theories that explain the origin of the universe have been searched for.
• God’s creations have been given importance by reflecting on their behaviors towards the environment.
• Cosmic Inflation Theory posits that the universe began with a singular explosion followed by a burst of inflationary expansion.
• The universe cooled, passing through a series of phase transitions and allowing the formation of stars, galaxies and life on earth.
• According to Cosmic Inflation Theory, the early universe was a rapidly expanding bubble of pure vacuum energy (no matter/radiation).
• The potential energy converted into kinetic energy of matter and radiation is a key aspect of Cosmic Inflation Theory.
• The Big Bang Theory was born of the observation that other galaxies are moving away from our own at a great speed in all directions, propelled by an ancient explosive force.
• Accretion Theory suggests that the solar system is formed by a nebula, a giant cloud of gas and dust that keeps rotating, causing collision and sticking together of dust particles, leading to the formation of larger chunks of matter.
• Accretion is the gradual increase in the size of an object by the build-up of the matter due to gravity, and the objects will get big enough to become planets and stars.
• Protoplanet Theory assumes that initially there is a dense interstellar cloud which will eventually produce a cluster of stars, with dense regions in the cloud forming and coalescing, resulting in stars with a low rotation.
• In Protoplanet Theory, the planets are smaller blobs captured by the star, with the small blobs having higher rotation than is seen in the planets, but theory accounts for this by having the planetary blobs split to give a planet and satellites.
• The Big Bang occurred because of the extremely hot, dense condition of matter, as proposed by Alan Guth in Cosmic Inflation Theory.
• Revolving around the Sun are 8 major planets with more than 170 satellites (moons), and currently 5 dwarf planets.
• Terrestrial planets are smaller, have higher density, are mostly made of rocky materials, have solid surface, few moons (if any), and no rings.
• Mercury, the closest planet to the Sun and has the shortest period of revolution (88 days), can only be seen from Earth just after sunset or just before sunrise, and its surface is cratered and crisscrossed by faults that formed as the planet originally cooled and contracted.
• Venus, the third-brightest object in the sky, is the hottest planet due to the large amount of carbon dioxide in the atmosphere, which produces a "greenhouse effect".
• Earth, the only planet with large amounts of surface water, an atmosphere that contains oxygen, a temperature climate, and living organisms (as far as we know), is the only astronomical object known to harbor life.
• Mars, named after the Roman god of war, has a reddish color due to fine-grain iron oxide minerals, clouds, and winds similar to Earth.
• Theory of Capture is a version of Jeans’s theory where the sun interacts with a nearby protostar, dragging a filament of material from the protostar.
• The low rotation speed of the sun is explained as being due to its formation before the planets.
• Formation of terrestrial planets through collision between the protoplanets close to the sun is explained in the Capture Theory.
• The giant planets and their satellites are explained as condensation in the drawn out filament in the Capture Theory.
• The collision of Theia and Earth is explained in the Capture Theory.
• The planets originated in a dense disk which formed from materials in the gas and dust cloud which collapsed to give the sun, according to the Modern Nebular Theory.
• The density of the disk has to be sufficient to allow the formation of the planets and yet thin enough for the residual matter to be blown away by the sun as its energy output increased, according to the Modern Nebular Theory.
• A complex system of moving masses held together by gravitational forces is the Solar System, with the center being a star called the Sun, which is the dominant mass.
• Steady State Theory, proposed by Fred Hoyle, posits that the universe has no beginning or end in time, and even though it is expanding, its appearance remains the same over time.
• Nitrogen and Oxygen, along with Hydrogen, Carbon, and Phosphorus, are constituent elements of biological molecules such as carbohydrates, protein, lipids, and nucleic acid.
• Earth’s climate and temperature are relatively stable, with a climate and temperature which are remarkably stable when compared with those of other planets.
• The average temperature of the Earth’s surface is 20 ˚C.
• The relative stability of Earth’s climate and temperature is important for the formation of biological molecules.
• Venus’s surface temperature is approximately 453 ˚C.
• Any trace of liquid water on Venus would have evaporated quickly.
• Mars’s temperature is a freezing -55 ˚C.
• Any aqueous solution contained in a cell at Mars’s temperature would have frozen, destroying the cell’s membrane, and leading to the death of the cell itself.
• Many people tend to think that the Earth is a sphere.