T1: Lec 1-4 Flashcards
(27 cards)
What is a planet?
celestial body that must orbit around a sun, be big enough that gravity forces it into a sphere, and has cleared way other objects near its orbit
What si an orbit?
a circular path around a sun roughly at the center
Seen in planets, binary star orbits, and how stars move in galaxies
Our solar system is in heliocentric orbit
What is a star?
a celestial body that produces its own light from nuclear reactions at its core
what is a galaxy?
come in many different shapes and forms, comprised of billions of different stars
What si the speed of light?
300,000 km/s
If a telescope is made 3x bigger than another, how much more light can it capture?
3x bigger and can capture 9x more light
Where is a crescent moon located?
closest to the horizon at sunrise and sunset
where is a full moon located
rises as the sun sets; high at midnight on the other side of the horizon
What is a constellation and how are they named?
pattern of stars in the sky that tell stories with stars moving across the sky only once a year.
Brightest stars in a constellation named with greek letter (e.g. Centaur is brightest star in Alpha Centauri)
what is the distinction of day, month, and year on Earth according to different rotational times?
1 day = 1 turn on Earth’s axis
1 month = 1 orbit of the moon around the earth
1 year = 1 orbit of earth around the sun
why do lunar years need to add a month every 3 years?
one Lunar month is 29.5 days, with 12 lunar months this only makes up 352 days (instead of 365). after 3 years, the mismatch of days then causes the lunar year calendar to have to add another month
Why do leap days exist?
Each year is actuallly 365.24 days long, so every 4 years we have to add one day in the solar calendar. However, every century the leap year is skipped. However! every 4 centuries, we do have a leap year.
Who made the julian calendar?
who made the Gregorian calendar?
Julius Ceasar
Pope Gregory XII by skipping 10 days ahead
Compare lunisolar calendar vs lunar calendar
Lunisolar uses a leap month every 3 years to catch back up with the solar calendar. A lunar calendar doesn’t do that, it just moves at its own pace with 12 lunar months
Explain 3 visuals in the night sky
- Elliptical movmeent of constellations that start lower each night
- Sun moving back and forth along horizon through the year during sunset, and the planets moving around the sun. (sun sets further north in winter and rises lower due to axil tilt of Earth)
- Planets move from night to night in their own orbits seen from Earth
what is matariki and why is it important?
Matariki - 9 visible stars (seen as tight group of stars, open cluster of stars)
Found in Taurus constellation around the month of July and June
Marks the changing season and those that have died
What are telescopes used for?
to see stars and fainter objects in space in more detail
Explain an arc second in a circle, in a minute, and in a degree
360* in a circle→ 60 arc minutes in a degree → 60 arc seconds in a minute→ 3600 arcsec in a degree
In 3 arc minutes = 180 arc second
how much can humans distinguish with their fully dialated pupil of 6mm
only 30 arc seconds
what did galileo discover?
Having lived from 1564-1642, Galileo discovered:
1. Phases of Venus - similar phases to moon, and orbits the sun
2. Moons of Jupiter
3. Saturn’s appearance
4. Craters of the moon
5. Milky way is made of stars
what is a refractor telescope?
bends light through lens with glass; heavy, creates chromatic aberration, and required long focal length
What is a reflector telescope?
reflect light off curved mirrors. Light doesn’t pass through, easier to support, and can be easily made bigger (also called “Newtonian Telescope”)
Is a refractor telescope or reflection telescope better?
reflection. it’s easier to capture more light as the diameter is easier to increase in the telescope. for refractor telescopes you can only increase the resolution by adding many more mirros and elongating the telescope. with reflection telescopes you only need to widen the diameter of the mirror lens.
Larger telescope diameter → more light captured → better resolution
A reflection telescope is 3x larger than another telescope. By how much will the resolution change by?
the resolution of the larger telescope will be 3x better than the other one, so the resolution will be able to show objects 3x smaller.
