Unit 4 Test: Space Flashcards
Smaller groups of stars making a pattern within a constellation
Asterism
A natural object out in space such as: Planets Comets Moons Stars Asteroids
Celestial bodies
- they appear to rotate around the earth
* they never set below the horizon
Circumpolar constellations
Because the earth revolves around the sun we see different parts of the sky every season
Seasonal constellations
The motion as it appears to our position on earth
: for example- the sun appears to be revolving around us
Apparent motion
Mars tracked from earth over a number of weeks appears to double back on itself before continuing onward. We call this path _________________
Retrograde motion
The orbiting of celestial bodies around a common point, (the earth revolves around the sun)
Actual motion
The spinning of a celestial body about an axis
Rotation
- he visualized the universe as being geocentric. This means the earth is the centre of the universe and everything else revolves around it.
- he believed that the earth was a sphere due to the curved edges observed during a lunar eclipse
Aristotle (383-168 B.C.E)
- based his model around his observations of mars
- mars orbital path creates a loop or s-shape in the sky
- his model showed each planet attached to a crystal sphere with its centre at earth
- each planet was not attached directly to its sphere but to an off-centre wheel (epicycle)
- accepted for nearly 1500 years
Ptolemy
- used to locate and predict the position of the Sun, Moon, and Stars
- Along with a compass, it could be used to describe the position of any celestial body in relation to the direction North and to the horizon
- allowed for more accurate observations to be made
The astrolabe
- believed in a heliocentric universe (sun at the centre)
- the earth rotated on its axis once daily and revolved around the sun once a year.
Copernicus (1473-1543)
-first person to view the “heavens” through a telescope
-allowed him to see objects about 20x closer
He observed:
-craters on the moon
-spots on the sun
Four “stars” orbiting jupiter (called the Galilean Moons)
Galileo(1564-1642)
- developed 3 laws of planetary motion
1. The orbits of planets are ellipses, with the Sun at one focus.
2. The law of areas: an imaginary line from a planet to the Sun will sweep over equal areas of the ellipse in equal intervals of time. Simply put; planets closer to the sun travel faster than those further from the sun
3. The time a planet takes to revolve around the Sun is directly related to how far away it is from the Sun.
Johannes Kepler(1571-1630)
- Developed the three laws of motion:
1. The law of interia
2. The law of force - mass x acceleration
3. The law of action and reaction - first to show that the force of gravity affects all celestial bodies, causing them to stay in orbit.
- invented the reflecting telescope which uses a curved mirror to focus the light to a point at an eyepiece
Sir Isaac Newton (1643-1727)
What are the planets mercury, venus, earth, and mars called?
Terrestrial planets
What are the planets jupiter, saturn, uranus, and neptune called?
Jovian planets
To be a planet it must……
- Orbit one or more stars
- Be large enough so it gravity holds it in place
- Be the only body in its orbital path
an ancient instrument used to locate and predict the positions of the sun, moons, planets, and stars
astrolabe
a distinctive pattern in the night sky formed by a group of stars; the pattern often looks like a familiar object, such as an animal
Constellation
The path followed by the sun through the sky, as seen from earth
Ecliptic
An oval shape for which the distance from one focal point to a point on the edge of the ellipse and then to the the other focal point is the same no matter which point on the edge of the ellipse yo choose.
Ellipse
Representing earth as the centre of the universe
Geocentric
Representing the sun as the centre of the universe
Heliocentric
The regular path of an object, such as a celestial body or an artificial satellite, around another body such as a star or a planet
Orbit
A celestial body that orbits one or more stars, is large enough that its own gravity holds it in a spherical shape, and is the only body occupying the orbital path
Planet
A measurement equal to the average distance between the sun and earth, about 150 million km
Astronomical unit
The theory that proposes that the universe formed approximately 13.7 billion years ago when an unimaginably tiny volume of space suddenly and rapidly expanded to immense size
Big Bang theory
A large sphere of incredibly tightly packed material with an extraordinary amount of gravitational pull created when a star collapses into itself
Black hole
Wavelengths of radiated light that are being constantly stretched (lengthened) as the light crosses the expanding universe
Cosmological red shift
Energy that is carried, or radiated, in the form of waves that range in length from short to long; types include X rays, ultraviolet radiation, visible light, microwaves, infrared waves and radio waves
Electromagnetic radiation
One of three basic galaxy shapes; a galaxy that ranges in shape from a perfect sphere to an elongated but flattened ellipse and contains some of the oldest stars in the universe
Elliptical galaxy
An enormous collection of gases, dust, and billions of stars held together by gravity
Galaxy
An optical telescope that was launched into earth orbit in 1990; provides images of distant galaxies and stars; light reaching its mirrors has not been distorted by the atmosphere
Hubble Space Telescope
One of three basic galaxy shapes; a galaxy that has neither spiral arms nor an obvious central core, made up of a mix of newly forming stars and old stars
Irregular galaxy
The distance that light, which moves at 300 000 km/s, travels in a year; equals about 9.5 trillion km
Light-year
A cloud of gas and dust in space
Nebula
States that the universe is closed and will go through a series of expansions and contractions, or Big Bangs and Big Crunches, in an ongoing cycle
Oscillating theory
A region of extremely high energy that develops as the supermassive black hole in the centre of a galaxy attracts more matter into itself
Quasar
A shifting of light from an object toward the red (longer wavelength) end of the spectrum as the object moves away from earth
Red shift
A dramatic, massive explosion that occurs when a large, high mass star collapses in on itself
Supernova
