Term
| What is the Celestial Sphere? |
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Definition
| It is what we see in the night’s sky, it is also how we humans see it ..Two-dimensional. |
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Term
| Where are the Celestial North and South Poles? |
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Definition
| They are north and south of the respective poles on earth..on the out side of the sphere. |
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Term
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Definition
| The distance a beam of light will travel in a year |
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Term
| Where is the Summer Solstice on the Celestial Sphere? |
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Definition
| Is when the Sun is furthest North of the Celestial Equator, this occurs on the first day of summer…June 21st plus or minus 2 days |
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Term
| Where is the Winter Solstice on the Celestial Sphere? |
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Definition
| Is when the Sun is furthest South of the Celestial Equator, this occurs on the first day of winter….December 21st plus or minus 2 days. |
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Term
| Where is the Autumnal Equinox? |
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Definition
| Is when the Sun crosses the Celestial Equator heading south, this occurs on the first day of Fall….September 21st plus or minus 2 days. Always 0 degrees, because the sun is on the equator. |
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Term
| Where is the Vernal Equinox? |
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Definition
| Is when the Sun crosses the Celestial Equator heading north, this occurs on the first day of Spring….March 21st plus or minus 2 days. Always 0 degrees, because the sun is on the equator. |
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Term
| What is an astronomical unit? |
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Definition
| The distance from the sun to the earth..reduced from 150,000,000 km = 1 astronomical unit. |
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Term
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Definition
| The apparent**(what we perceive but is not really happening) path of the Sun across the Celestial Sphere only during the year. |
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Term
| Where is the Ecliptic in the sky? |
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Definition
| It runs at a constant 23.5-degree angle to the Celestial equator and it always intersects the Equinoxes (both Vernal and Autumnal). |
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Term
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Definition
| The time it takes the Earths axis to make a full rotation, and taking into consideration the gravitational pull of the Moon and Sun on the equatorial bulge. It takes 26,000 years. |
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Term
| What causes the change of Seasons? |
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Definition
| The seasons occur because the earth's axis is tilted as the earth orbits around the sun. |
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Term
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Definition
| Time for the cycle of the Moons Phases (29.5 days) by way of the Sun and relative to the position of the Sun too. |
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Term
| What is a Sidereal Month? |
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Definition
| Time for the Moon to revolve around the Earth (27.3 days) |
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Term
| Why are the Synodic and Sidereal different in length? |
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Definition
| Because the Sidereal represents the time it takes for the moon to revolve once around the earth and then the Synodic has to do with the phases that the Moon goes through as it travels around the earth. |
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Term
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Definition
| It is where the Earths shadow passes over the Moon, very common; the Moon will also appear reddish in color. This can only occur during a full Moon. |
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Term
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Definition
| It is when the Moons shadow moves across the Earths surface, as seen from the Earth – the Moon moves in front of the Sun. This can only occur during a new Moon. |
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Term
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Definition
| The central, completely dark portion of a shadow. |
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Term
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Definition
| The portion of a shadow in which only part of the light source is covered by the shadow-making body. |
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Term
| What is an Annular Eclipse? |
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Definition
| An eclipse of the Sun in which the Moon is too distant to cover the Sun completely so that a ring of sunlight is seen around the Moon at mideclipse. |
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Term
| What type of Eclipse would you see from the Umbra? |
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Definition
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Term
| What type of Eclipse would you see from the Penumbra? |
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Definition
| Partial Eclipse and Penumbral Eclipse |
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Term
| What is Geocentric Cosmology? |
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Definition
| The belief that the Earth is the center of the Universe. |
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Term
| What is Heliocentric Cosmology? |
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Definition
| A theory of the formation and evolution of the solar system with the Sun at the center of the Universe. |
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Term
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Definition
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Term
| Who disproved it and how? |
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Definition
| Aristarchus proposed a more straightforward explanation of planetary motion namely, that all the planets, including Earth, revolved around the Sun. The retrograde motion of Mars in this HELIOCENTRIC COSMOLOGY occurs just because the faster-moving Earth overtakes and passes the red planet |
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Term
| What contribution did Ptolemy make to Astronomy? |
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Definition
| He perfected the idea, with regards to the planets; they move backwards (retrograde)….From the 1st Century. Also that earth was the Center of the Universe. |
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Term
| What contribution did Nicolaus Copernicus make to Astronomy? |
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Definition
| Lived from 1473-1543, He developed a heliocentric theory of the known universe and just before his death in 1543 he published this work however his theory was flawed in that he assumed that the planets had circular orbits around the Sun. The planets closest to the sun orbit faster than those further away. Created order to the planets: Mercury, Venus, Earth, Mars, Jupiter, and Saturn. Noticed that the stars are very, very far away. |
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Term
| What contribution did Aristarchus make to Astronomy? |
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Definition
| Lived in 300 BC, Discovered that the Moon is smaller than the earth. Concluded that our Universe is Heliocentric (Sun Centered). |
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Term
| What contribution did Galileo make to Astronomy? |
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Definition
Lived from 1564-1642, first Astronomer to use a telescope (1610)
Also discovered the phases of Venus, moons of Jupiter, the rings of Saturn, mountains and craters on the Moon, that the Milky Way is made up of stars and Sunspots on the Sun. First observational proof that Copernicus was correct our universe is Heliocentric. |
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Term
| What contribution did Johannes Kepler make to Astronomy? |
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Definition
| Lived from 1571-1630, was the observational assistant for Brahe. Professor for one day. Personally responsible for Keplers Laws of Planetary Motion (3 of them) (1609-1619) |
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Term
| What contribution did Isaac Newton make to Astronomy? |
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Definition
| Lived from 1642-1727, was not a contemporary of Galileo, Newton was born the day that Galileo died. Created the Newton Laws of Motion and Gravitation. |
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Term
| What contribution did Eratosthenes make to Astronomy? |
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Definition
| Lived in 200 BC. Nailed the size of the Earth within 5%..he did it by measuring the Suns angles to detect how big the Earth was. |
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Term
| What contribution did Tyco Brahe make to Astronomy? |
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Definition
| Lived from 1546-1601, developed the best Pre-Telescope, was the greatest observer of the pre-telescope: his observational precision was down to that of 1 arc minute (very precise). Disproved the theory of the crystal sphere. Discovered a new star (Supernova). Did not believe that the universe was Heliocentric. |
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Term
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Definition
Keplers first law states that: The planets orbits are ellipses with the sun..which means that the shapes of the ellipses have two extremes, the roundest is when both focus (foci) merge and that is a circle the other is the most elongated ellipse which is almost a straight line and then everything in between the two. The ellipses of the Sun is ever changing.
Keplers second law states that: The planets in their orbits sweep out equal areas in equal time intervals….which means that as the planets travel around in orbit the speed changes and will vary depending how close it is to the Sun. The closer it is to the Sun the faster it goes and the more further away it is the slower it will go. But the orbit will take the same time every time.
Keplers third law states that: p(2)=a(3) which means….p=orbital period in years and a=semi-major axis in AU’s
The Larger the orbit the slower the Planet will move..for example:
Earth P=1 A=1
Jupiter P=11.8 A=5.2 (Jupiter has an orbit that is 5 times larger
Took 10 years to come up with this 3rd Law. |
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Term
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Definition
Newtons first Law states that: An object at rest or traveling in a straight line at a constant speed remains in that state unless acted upon by an outside force (gravity). Which means…this example..if you put a soccer ball in your hands and press on both sides equally it represents a balanced pair of forces acting on the ball (you are exerting no net external force on that ball) However, when your foot hits a soccer ball and the ball sails away, your foot has exerted a net external force on that ball.
Newtons second Law states that: F=ma which means that…if a force acts on an object, the object will experience an acceleration. An example is: The force with which I am pressing down on the ground is 183lbs, but I way 183lb only on earth. I would weigh 30.5 lbs on the Moon, which has less mass and so pulls me down with less gravitational force.
F=force
M=mass
A= acceleration
Acceleration is a change in velocity
Velocity is represented in speed and direction
Newtons third Law states that: For every action (force) there is an equal and opposite reaction (force). An example is: The means that if your foot presses into the floor you would exert energy to take a step forward.
Newtons Law of Gravity states that:
F=GM{1}M{1}
________________
R(2)
G= Universal Gravitational Constant
**As mass increases force increases
**As mass decreases force decreases
This happens between two objects
Center to Center |
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Term
| How are Newtons and Keplers Laws Related?? |
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Definition
Newtons Modification to Keplers Third Law:
(M{1} + M{2})P(2)=a(3)
masses in Solar Masses
(Solar mass is equal to the Moons of the Sun) |
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Term
| What type of detectors do or have astronomers used? |
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Definition
Astronomers through the ages have used Telecopes; they have used Reflecting (uses a mirror) and Refracting (uses a lens to bend the light).
The have also used Convex lens telescope.
They have used telescopes in space ..such as the Hubble.
They have also used Radio Telescopes.
They have also used X-Ray telescopes. |
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Term
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Definition
| Charge Coupled Devices-highly effective electronic light detectors |
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Term
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Definition
| Very Large Array of Radio Telescopes…in New Mexico which consisted of 27 total on railroad tracks to help with ease of moving them around. |
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Term
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Definition
| Very Long Baseline Interferometry of radio telescopes. This consists of 10- 25meter radio telescopes that can be linked across the US from Hawaii to New Hampshire. This arrangement has a resolving power of .001” |
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Term
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Definition
| Hubble Space Telescope, reflecting Cassagrain Telescope. Takes 1 ½ hr to go around the earth. #1 reason for this telescope is that it is above the atmosphere. |
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Term
| Why is Light-Gathering Power more important than Magnifying Power for telescopes? |
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Definition
| Because the more light you have the better resolution your image is. If your aperture is big then you have a much better bright picture. You will have fewer distortions and no light loss like you would have in a Magnification Telescope or Reflective telescope. When you magnify and image the more you risk the distortion of the image. |
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Term
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Definition
| A perfect absorber of all wavelengths of Electromagnetic radiation. |
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Term
| What astronomical objects act like these theoretical objects? |
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Definition
| Would be the Sun and the other stars in the galaxy. |
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Term
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Definition
| The dominant (wavelength) from a Blackbody is inversely proportional to its temperature. |
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Term
| What is Stefan-Boltzmann Law? |
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Definition
A blackbody’s energy output is proportional to its Temperature to the 4th Power.
Hot BB-gives off short wave lengths
Cool BB-gives off long wavelengths |
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Term
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Definition
| This is how to calculate photons energy. It is the relationship between the energy of a photon and its wavelength. The energy of a Photon never changes except for the wavelength. |
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Term
| Why are these effects important to Astronomers? |
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Definition
| Because these ideas are invaluable for understanding how stars of various temperatures interact with gas and dust in space |
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Term
| What is an Absorption Spectrum? |
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Definition
| Dark lines superimposed on a continuous spectrum. You might be missing some protons. Where the part of the Spectra collapses. |
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Term
| What is the Emission Spectrum? |
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Definition
| You would only see a handful of the colors..mostly black. |
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Term
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Definition
Law #1 A solid, liquid or gas produces a continuous spectrum. Complete rainbow of colors without any spectral lines. This is a blackbody spectrum.
Law #2 A rarefied (opposite of dense) gas produces an emission line spectrum- a series of bright spectral lines against a dark background.
Law #3 The light from an object with a continuous spectrum that passes through a cool gas produces an absorption line spectrum –a series of dark spectral lines among the colors of the rainbows. |
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Term
| Why are they so important? |
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Definition
| Will really help us determine the make up of stars. |
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Term
| What sort of information can an astronomer get from the Spectrum of a star? |
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Definition
| To know the gas make up of a star. Tells us the chemical composition of the Sun’s lower atmosphere and that of Earth’s atmosphere. |
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Term
| What is the Doppler Effect? |
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Definition
| The change in wavelength of radiation due to relative motion between the source and the observer along the line of sight. |
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Term
| How do Astronomers use it? |
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Definition
| To develop models that provide numerous insights into the ages, masses, distances, internal activity, rotation rates and companion objects of stars among other things. |
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