Know your planet

To begin with, let’s ask ourselves one question and let’s go through and see what some scientists say about the origin of universe from the scientific not biblical point of view of it and so far what findings have been achieved. What is the universe? The universe is a huge wide-open space that holds everything from the smallest particle to the biggest galaxy. (A galaxy contains stars, gas, and dust which are held together as a group by gravity. There may be millions, or even billions, of stars in one galaxy. There are billions of galaxies in the universe). No one knows just how big the Universe is. Astronomers try to measure it all the time. They use a special instrument called a spectroscope to tell whether an object is moving away from Earth or toward Earth. Based on the information from this instrument, scientists have learned that the universe is still growing outward in every direction. Scientists believe that about 13.7 billion years ago, a powerful explosion called the Big Bang happened. This powerful explosion set the universe into motion and this motion continues to expand today. Scientists are not yet sure if the motion will stop, change direction, or keep going forever. It’s still like a mystery but scientific findings are always continuing. To understand more about the size of universe and galaxies, first let’s also see the size of a galaxy its self. What is the size of a galaxy? Galaxies are labelled according to their shape. Some galaxies are called “spiral”, because they look like giant pinwheels in the sky. The galaxy we live in, the Milky Way, is a spiral galaxy. Some galaxies are called “elliptical”, because they look like flat balls. A galaxy may be called “irregular” if it doesn’t really have a shape. A new type of galaxy was discovered recently, called a “starburst” galaxy. In this type of galaxy, new stars just seem to ‘burst out’ very quickly. The size of a galaxy is measured using a measurement called light year (light-year is the distance light travels in one year. It is 9.5 trillion (9,500,000,000,000) kilometres. The size of a galaxy may be as little as a thousand light-years across or as much as a million light-years across. Remember the speed of light is approximately 300,000 kms/second. We have seen that galaxies are made up of millions or billions of stars, gases and dust. This takes us to another interesting question. What is a star? A star is a celestial body of hot gases that radiates energy derived from thermonuclear reactions in the interior. Our sun is also a star or our star for that matter. Stars are born and time comes and they die.Temperature of Stars You might be surprised to know that the colour of stars depends on their temperature. The coolest stars will look red, while the hottest stars will appear blue. And what defines the temperature of a star? It all comes down to mass. The most common stars in the Universe are the relatively tiny red dwarf stars. These stars can have as little as 7.5% the mass of the Sun, and top out at about 50%. Red dwarfs use their stores of hydrogen fuel very slowly; it’s believed that a red dwarf star with about 10% the mass of the Sun may live for 10 trillion years or more. Our own Sun will only live for about 12 billion years. Red dwarf stars have a surface temperature of less than 3,500 Kelvin, and this is why they appear red to our eyes. Our own Sun is classified as a yellow dwarf star. It has a surface temperature of about 5,800 Kelvin. Because of this temperature, the bulk of the light we see streaming from the Sun is yellow/white. Our Sun has been in the main sequence phase of its life for 4.5 billion years, and it’s expected to last another 7 billion years or so. The hottest stars are the blue stars. These starts at temperatures of about 10,000 Kelvin, and the biggest, hottest blue super giants can be more than 40,000 Kelvin. In fact, there’s so much energy coming off the surface of a blue star that many could actually be classified as ultraviolet stars; it’s just that our eyes can’t see that high into the spectrum. Our sun looks different from the rest of the stars both in size and in colour not because it’s bigger than the rest of the stars or hotter but because it’s very nearer to us and the temperatures it emits can easily be felt on planet earth. Having seen that the sun is our star, it also has got several planets and rotates around it including our planet earth. Other stars also have got their own planets that rotate around them. and many have been observed to have them. If you were on a planet in a galaxy far away you would be able to see our sun as an individual star, the distance would be too great, but from a planet of a star in our own galaxy you could see our sun as being just another star. How does our sun look like with its planets (solar system)? The sun is the biggest object in the solar system and all other planets rotate around the sun. The sun itself also rotates around its own axis. All other planets rotate around their own axis. This means that our planet earth rotates on its own axis and at the same time it rotates around the sun. All planets rotate around the sun and they also rotate around their own axis but at different speeds. The earth rotates on its axis once each day. Since the circumference of the earth at the equator is 24,901.55 miles, a spot on the equator rotates at approximately 1037.5646 miles per hour (1037.5646 times 24 equals 24,901.55) (1669.8 km/h). At the North Pole (90 degrees north) and South Pole (90 degrees south), the speed is effectively zero since that spot rotates once in 24 hours, a very, very slow speed. To determine the speed at any other latitude, simply multiply the cosine of the degree latitude times the speed of 1037.5646. What is the speed at which the earth rotates around the sun? The Earth rotates once in a few minutes under a day (23 hours 56 minutes 04. 09053 seconds). This is called the sidereal period (which means the period relative to stars). The sidereal period is not exactly equal to a day because by the time the Earth has rotated once, it has also moved a little in its orbit around the Sun, so it has to keep rotating for about another 4 minutes before the Sun seems to be back in the same place in the sky that it was in exactly a day before. An object on the Earth’s equator will travel once around the Earth’s circumference (40,075.036 kilometers) each sidereal day. So if you divide that distance by the time taken, you will get the speed. An object at one of the poles has hardly any speed due to the Earth’s rotation. (A spot on a rod one centimeter in circumference for example, stuck vertically in the ice exactly at a pole would have a speed of one centimeter per day!). The speed due to rotation at any other point on the Earth can be calculated by multiplying the speed at the equator by the cosine of the latitude of the point. (If you are not familiar with cosines, I wouldn’t worry about that now, but if you can find a pocket calculator which has a cosine button you might like to try taking the cosine of your own latitude and multiplying that by the rotation speed at the equator to get your own current speed due to rotation!). Ends