Answer Flashcards
What is the definition of Nebula?
A nebula is an enormous cloud of dust and gas occupying the space between stars and acting as a nursery for new stars.
what is the definition of Galaxy?
A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
what is the definition of Light year?
A light-year is the distance light travels in one Earth year. One light-year is about 6 trillion miles (9 trillion km). That is a 6 with 12 zeros behind it!
what is the definition of Hertzsprung-Russell Diagram
The Hertzsprung-Russell diagram is a graph of many stars. It shows the relation between stars’ luminosity (that is, how bright they are) and their temperature (how hot they are).
what is the definition of Supernova
A supernova is a large explosion that takes place at the end of a star’s life cycle. A supernova is the explosion of a star. It is the largest explosion that takes place in space.
what is a definition of Red shift?
the wavelength of the light is stretched, so the light is seen as ‘shifted’ towards the red part of the spectrum.
what is the Hubble’s law?
a law stating that the red shifts in the spectra of distant galaxies (and hence their speeds of recession) are proportional to their distance.
how are stars born?
A star is born when atoms of light elements are squeezed under enough pressure for their nuclei to undergo fusion. And once the fusion reactions begin, they exert an outward pressure. As long as the inward force of gravity and the outward force generated by the fusion reactions are equal, the star remains stable.
what is a stars lifetime?
Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is considerably longer than the age of the universe.
outline what an Exoplanet is.
a planet that orbits a star outside the solar system. Exoplanets are very hard to see directly with telescopes. They are hidden by the bright glare of the stars they orbit. So, astronomers use other ways to detect and study these distant planets.
what is the definition of Planetes Asteres?
The word planet comes from two related Greek words, planēs (whence planētes asteres “wandering stars, planets”) and planētēs, both with the original meaning of “wanderer”, expressing the fact that these objects move across the celestial sphere relative to the fixed stars.
what is Parallax effect
Parallax is the perceived change in position of an object seen from two different places. In astronomy, annual parallax is the only direct way to measure distance to stars outside the solar system. In essence, parallax is the perceived shifting phenomenon which occurs when an object is viewed from different positions.
what is the difference between Geocentric vs heliocentric model
The geocentric model says that the earth is at the center of the cosmos or universe, and the planets, the sun and the moon, and the stars circles around it. The early heliocentric models consider the sun as the center, and the planets revolve around the sun.
what is the Ring Of Fire?
The Ring of Fire, also referred to as the Circum-Pacific Belt, is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. The majority of Earth’s volcanoes and earthquakes take place along the Ring of Fire.
what is the definition of Apparent and Absolute Magnitude? how do they differ?
Astronomers define star brightness in terms of apparent magnitude — how bright the star appears from Earth — and absolute magnitude — how bright the star appears at a standard distance of 32.6 light-years, or 10 parsecs.
