Earth and the Moon are part of the universe, as are the other planets and their many dozens of moons. Along with asteroids and comets, the planets orbit the Sun. The Sun is one among hundreds of billions of stars in the Milky Way galaxy, and most of those stars have their own planets, known as exoplanets.
In the span of a single human lifetime, space probes have voyaged to the outer solar system and sent back the first up-close images of the four giant outermost planets and their countless moons; rovers wheeled along the surface on Mars for the first time; humans constructed a permanently crewed, Earth-orbiting space station; and the first large space telescopes delivered jaw-dropping views of more distant parts of the cosmos than ever before. In the early 21st century alone, astronomers discovered thousands of planets around other stars, detected gravitational waves for the first time and produced the first image of a black hole.
The Sun, Stars and Planets (Tell Me About)
Our Sun (a star) and all the planets around it are part of a galaxy known as the Milky Way Galaxy. A galaxy is a large group of stars, gas, and dust bound together by gravity. They come in a variety of shapes and sizes. The Milky Way is a large barred spiral galaxy. All the stars we see in the night sky are in our own Milky Way Galaxy. Our galaxy is called the Milky Way because it appears as a milky band of light in the sky when you see it in a really dark area.
Another clue comes when astronomers map young, bright stars and clouds of ionized hydrogen in the Milky Way's disk. These clouds, called HII regions, are ionized by young, hot stars and are basically free protons and electrons. These are both important marker of spiral arms in other spiral galaxies we see, so mapping them in our own galaxy can give a clue about the spiral nature of the Milky Way. There are bright enough that we can see them through the disk of our galaxy, except where the region at the center of our galaxy gets in the way.
All of the planets in our solar system orbit around the Sun. Planets that orbit around other stars are called exoplanets. Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit.
In 2009, NASA launched a spacecraft called Kepler to look for exoplanets. Kepler looked for planets in a wide range of sizes and orbits. And these planets orbited around stars that varied in size and temperature.
So far, thousands of planets have been discovered by the Kepler mission. And more will be found by NASA's Transiting Exoplanet Survey Satellite (TESS) mission, which is observing the entire sky to locate planets orbiting the nearest and brightest stars.
At night time, there are millions of tiny sparkling lights in the sky some are stars and some others are planets. It can be difficult the tell the difference between a star and a planet sometimes, but what is the real difference? By definition, a star is a celestial object that emits its own light due to a chemical reaction at its core. Some stars can appear brighter than others due to their size and their distance from earth, click here to read about the 10 brightest stars in the night sky. A planet is a celestial body that orbits around the star in its solar system and gets its glow from the suns light reflecting from the planets face.
In Ancient Astronomy, in order to distinguish whether or they were looking at a planet or a star, astronomers would study the movement of that specific source of light over the course of a few nights. Planets, like the sun and the full moon, rise and set and follow a celestial path across the night sky. While stars do move, they move in a differently in comparison to the planets in our solar system. Stars move in a circular pattern around the North Star, therefore, if the light that you see appears to move in a straight line over the course of a few nights, it is most likely a planet!
If you have figured out the difference between the stars and planets in the night sky, how can you tell which planet that you are looking at? One way to tell the difference is by observing the colour of the planet. Not all the planets in our solar system have a specific colour, however the most prominent planets in the night sky can appear to have some sort of colouration. It is recommended to use a telescope on a clear night if you are trying to distinguish the colour difference between the planets in the night sky.
Mercury is the smallest of the planets that is visible to the naked eye and shines as an evening star in the western sky, setting around about an hour after the sun sets. In the eastern sky, Mercury can be seen rising about one hour before the sun. If you are looking for Mercury in the night sky, you must have a clear, unobstructed view of the horizon. You may find that Mercury appears as a bright star with a yellowish hue.
Gravity is what holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon pulls the seas towards it, causing the ocean tides. Gravity creates stars and planets by pulling together the material from which they are made.
Stars are the most widely recognized astronomical objects, and represent the most fundamental building blocks of galaxies. The age, distribution, and composition of the stars in a galaxy trace the history, dynamics, and evolution of that galaxy. Moreover, stars are responsible for the manufacture and distribution of heavy elements such as carbon, nitrogen, and oxygen, and their characteristics are intimately tied to the characteristics of the planetary systems that may coalesce about them. Consequently, the study of the birth, life, and death of stars is central to the field of astronomy.
Navigation is the art and science of determining the position of a ship, plane or other vehicle, and guiding it to a specific destination. Navigation requires a person to know the vehicle's relative location, or position compared to other known locations.Navigators measure distance on the globe in degrees. Understanding latitude and longitude are very important in navigation. Latitude is a north-south position measured from Earth's Equator and longitude is an east-west position measured from the prime meridian.There are many different navigation techniques. People have been using some of them for thousands of years.The earliest navigation methods involved observing landmarks or watching the direction of the sun and stars. Few ancient sailors ventured out into the open sea. Instead, they sailed within sight of land in order to navigate. When that was impossible, ancient sailors watched constellations to mark their position. The ancient Minoans, who lived on the Mediterranean island of Crete from 3000 to 1100 B.C.E, left records of using the stars to navigate, for instance.Compasses, which indicate direction relative to the Earth's magnetic poles, are used in navigation on land, at sea, and in the air. Compasses were being used for navigation by the 1100s C.E., and are still the most familiar navigational tools in the world.Dead ReckoningDead reckoning involves estimating a current position based on a past position. Dead reckoning factors in speed, time, and direction of travel. When used in sailing, it does not take into account wind speeds or ocean currents. However, the only reference point in dead reckoning is the past position. This can make it difficult to realize when mistakes are made during travel.Celestial NavigationFor sailors, celestial navigation is a step up from dead reckoning. This technique uses the stars, moon, sun, and horizon to calculate position. It is very useful on the open ocean, where there are no landmarks.Navigators must be familiar with the different constellations at different times of the year, as well as the different constellations in the Northern and Southern Hemispheres. The most familiar constellation in the Southern Hemisphere, for instance, is the Southern Cross. The stars in this constellation are never visible in the Northern Hemisphere above the tropics. The Big Dipper, a familiar constellation in the Northern Hemisphere, is not visible in the Southern Hemisphere.Navigators using this method need a tool such as a sextant to measure the angle between objects in the sky and the horizon. They also need an accurate clock and an almanac giving the positions of celestial bodies.NASA and other space agencies continue to use sophisticated celestial navigation for many of their missions outside Earth's atmosphere. The astronauts and engineers of the Apollo program used celestial navigation to chart their way to the moon and back. The Mars Exploration Rover also uses celestial navigation to communicate information back to engineers and researchers on Earth.PilotingPiloting relies on fixed visual references to determine position. This is probably the most familiar type of navigation. With this technique, the pilot must be able to recognize visual markers or identify them using maps or charts. If the pilot misidentifies the markers, he or she could take the vessel off course. Pilots also employ radar or global positioning system (GPS) technology if visibility is poor.Pilots are one of the most important crew members on seagoing vessels. Pilots navigate ships through difficult passages, such as narrow channels, stormy river mouths, and harbors with heavy ship traffic. With millions of dollars of cargo (such as cars, oil, or military troops) on ships larger than a football field, the pilot must be calm and responsible. He or she must understand the weather, the seabed or lakebed, the channels of a river, and trade winds and currents.Radio NavigationRadio navigation is similar to celestial navigation, except it replaces objects in the sky with radio waves being broadcast. The navigator can tune into a radio station and use an antenna to find the direction of the broadcasting radio antenna. Position can be determined by measuring the time it takes to receive radio signals from the stations of known locations on the ground or aboard satellites.Radar is a type of radio navigation. It originally stood for Radio Detection And Ranging. Radar is a system that measures the time it takes to bounce electromagnetic waves off an object and back to a receiver. The waves that reflect back to the receiver indicate the object's distance.GPSGPS, or global positioning system, is a satellite-based navigation system. While the GPS system is funded and controlled by the U.S. government's Department of Defense, anyone with a GPS receiver can use it. The earliest GPS system was launched between 1978 and 1985 with 11 satellites. It now includes about 24 satellites that orbit Earth and send radio signals from space.The system works much like radio navigation. A GPS device receives a signal from the satellites, and it calculates position based on the time it takes for the signal to transmit and the exact position of the satellites. It is a highly accurate navigation tool. 2ff7e9595c
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