Astronomy is the scientific study of celestial objects such as stars, comets, planets, and galaxies. It is derived from Greek words astron and nomos which mean 'star' and 'law', respectively. It is related with the formation and development of the universe, motion of celestial objects, and their interrelationships.
Since the 20th century, the field of astronomy has been divided into two branches: observational and theoretical. Observational astronomy emphasizes on acquiring and analyzing the data by using basic principles of physics. Theoretical astronomy focuses on the development of computer or analytical models to explain astronomical objects and phenomena. These branches complement each other, and have indeed been used together most often.
Meet the Sun
The Sun is approximately 4.5 billion years old, and produces 383 billion trillion kilowatts of energy.
Sunlight takes 8 minutes to reach the Earth, and is responsible for the ocean currents and weather patterns observed on our planet.
The Earth orbits the Sun in an uneven, elliptical orbit, and the distance between them varies depending on where exactly the Earth lies in that orbit.
The Sun is not particularly large for a star, but it still accounts for over 99% of the total matter in our solar system!
Solar wind produced by the Sun extends to about 50 AU, where 1 AU (Astronomical Unit) is the distance from Earth to the Sun.
Lightning seen on the Earth is nearly 3 times hotter than the surface of the Sun.
In 2 - 5 billion years, the Sun will expand and engulf Mercury and possibly Venus. This will destroy all life on Earth, but it's just a natural stage in the life of a star.
Meet The Moon
The Moon is the only non-Earth object upon which man has walked.
Dr. Eugene Shoemaker was a pioneering planetary scientist and geologist. His love for the Moon was so much that after his death, his ashes were scattered over the Moon by the Lunar Prospector spacecraft, in 1999.
The Moon is moving away from the Earth at a rate of 3.78 cm per year.
The Moon is tidally locked with the Earth, which means that it takes the same amount of time to revolve around the Earth as it takes to rotate one full circle. This results in only one side of the Moon being visible to us.
How Much Do You Know About Stars?
There are estimated to be nearly 7 x 1022 stars in the universe.
Some of the stars in the sky are so far from the earth that the light from them takes billions of years to reach us.
Proxima Centauri is the closest star to our solar system; it is nearly 4.22 light years away.
Depending upon how hot a white dwarf star is, its color may vary from blue, white, yellow, or red.
Supernova explosions are capable of destroying an entire star.
Pulsar, a type of neutron star, discovered in 1967, emits radio waves in 'pulses'. The frequency of these pulses is so stable that some pulsars can be used as accurate timekeepers―as accurate as atomic clocks.
Polaris, the north star, is the only star in the sky that doesn't appear to move from night to night.
Facts About Planets
Mercury is the smallest planet in the solar system, and has no moon. It can get as hot as 427°C (800.6°F). One year on Mercury is equal to just 88 earth days. It is named after the Roman God of Commerce.
Venus is the only planet that rotates from east to west. A year on this planet is equal to 225 days on the Earth.
The Earth is nearly 93 million miles away from the Sun.
It takes about 16 million horsepower to break the earth's gravitational pull.
According to scientists, in around 5 billion years, a day on the Earth will be 48 hours long due to tidal drag.
The planet Neptune was discovered more than 150 years ago, in 1846, and since then, it has only completed one full orbit around the Sun, as one year on Neptune equals 165 earth years!
Pluto, the erstwhile planet, was determined to be a dwarf planet by a committee of astronomers in 2006. This was due to it being a part of the Kuiper belt, and smaller than at least one other discovered trans-Neptunian object, the dwarf planet Eris.
The reclassification of Pluto has drawn strong reactions from the scientific community as well as the public, and many still obstinately consider it a planet.
Astronomy is certainly among the most interesting branches of science, and is filled with many interesting facts.