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Flashcards in Facts I Must Know Deck (81):

What is the diameter of the moon?



What is the distance from the Earth to the Moon?

380,000 km


What is the distance from Earth to the Sun?

150 million km


What is the diameter of the sun?

1.4 million km


What are rilles?

Valleys or trenches found on the moon


What are wrinkle ridges?

Feature found on lunar Maria, low sinuous ridges found on moon surface. They can extend up to 100km and were created when basaltic lava cooled and contracted


What are mascons?

A region of excess gravitational attraction on the moon


What is a dome?

A type of shield volcano on the moon


What is a Maria?

Large basins filled with lava that became solid, look like seas from Earth


What are sinuous?

Collapsed lava tube channels up too 5km wide


What is the chromosphere?

An irregular layer above the photosphere where the temperature rises up to 20,000 degrees Kelvin and hydrogen emits a reddish colour


What does the butterfly diagram show?

The sunspot cycle and how over 11 years they make their way from the poles to the equator then repeat again


How long does the sun rotate at the poles? And the equator?

36 at poles 25 at equator


What is the equation of time?

Eot = apparent sun - mean sun


What is the photosphere?

The luminous envelope of a star which it’s light and heat radiate


How hot is the photosphere?

5,800 degrees Kelvin


What is the corona?

An aura of plasma that surrounds stars and extends for millions of km into to atmosphere as can only be seen in a solar eclipse


In a lunar eclipse where are the sun, earth and moon located?

The Earth is in between the moon and sun


In a solar eclipse where are the moon, sun and earth located?

The moon is between the sun and Earth


What is how far north and south measured by? What about East and west?

Latitude and longitude


What is the point directly above you called?

The zenith


What are the 4 Maria on the east of the moon called?

Sea of Crises, tranquillity,fertility and serenity


Name a lunar terrae

The Apennine Mountains


Name a lunar crater

Tycho, Kepler and Copernicus


What is fusion?

The process of joining 2 or more things together to form a single entity


What is a sunspot?

A temporary phenomena on the photosphere of the sun that appear to have darker spots, are cooler, than surrounding regions. This is due to concentrations of magnetic field flux that inhibit convection


What is the solar wind?

A stream of charged particles flowing out from the sun through the solar system at speeds as high as 900km/s and at temperatures of 1 million degrees Celsius


How long does the lunar (rotational) cycle take? What about a sidereal (orbital) cycle?

One cycle is 29.5 days as the Earth has moved round the sun whilst the moon is orbiting so it has to catch up, one sidereal/full rotation of the moon, is 27.3 days


What is the diameter of the Earth?



When using the equation EOT = AST - MST to find the mean solar time (of where you are, MST = AST - EOT ) if your watch (set to GMT) is ahead of the MST calculated you are where of the prime meridian? What about if your watch is behind?

Watch is ahead you are west, behind is East


What is the closest point Earth gets to the sun in orbit called? What about the furthest?

Closest is called the Perihelion, furthest is called the Aphelion


What is the closest and furthest point the moon gets to the Earth in orbit called?

Closest is the Perigee and furthest is the Apogee


What temperature is the corona?

2 million kelvin


How long is a solar day? What about a sidereal day? What’s the difference?

Sidereal is 23 hours 56 minutes, solar is 24 hours. This is because the Earth is constantly moving around the sun so once we have moved and rotated we need to catch up by one degree which takes 1 degree (4 minutes)


What is the proper name for the northern lights?



What are aurorae caused by?

Light given off as particles from solar wind interact with atmosphere after spiralling in near the poles


What is the penumbra and umbra in moons and suns?

The umbra is the area of deepest shadow in either the centre of a sunspot or the shadow behind the Earth and a penumbra is the less dark shadow on the rim of a sunspot or the rim of the earths shadow


What is H-alpha?

A wavelength the sun gives of due to the hydrogen it emits (656 nm), this can be observed through a telescope with a fitted filter


What are the 3 types of eclipses?

Total, partial and annular


What is the plain the Earth orbits the sun called?

The ecliptic, 67 degrees from the axis of earths rotation


Which of the 2 tropics , cancer and Capricorn, appear furthest north?



How many signs of the zodiac are there? Give some examples

12, Aquarius , Capricorn , lea, cancer, Pisces, Virgo, Aries, Taurus , Gemini , Libra, Scorpio and Sagittarius


What is the zodiacal band?

The region in the night sky which the moon, planets and constellations of the zodiac are located


Where is your sign of the zodiac when you are born?

Behind the sun


What is the mean sun?

For a given time where the sun should be on average across the year isn’t the sky


Where is longitude measured from?

The prime meridian in Greenwich, London


What does circum polar mean?

It can be seen throughout the year, it is far enough north or south, such as Polaris is north


What is magnitude?

How bright a star is


What is the equation for the apparent magnitude of a star? What about the equation to figure out absolute magnitude?

Apparent magnitude is m= M-5 +5log d. Where apparent magnitude is m and absolute magnitude is M and d is distance is parsecs for both equations. Absolute magnitude formula is M=m + 5 - 5logd


What is apparent magnitude? What about absolute?

Apparent magnitude is the brightness of a star from Earth, absolute magnitude is the brightness of a star from the distance of 10 parsecs away


What is declination?

How high/below a star is from the celestial equator


What is right ascension?

How far around a star is, like longitude for stars, it is from 0 to 24 and get larger as stars move across the sky east until it starts again


What is a terrae?

A lunar feature of hills and mountains


What are the 3 main layers of the suns atmosphere?

Photosphere, chromosphere and the corona


Which is the lowest of the main 3 layers of the suns atmosphere?

The photsphere


What is the top layer of the suns atmosphere?

The corona, followed by the chromosphere then the photosphere


How thick is the photosphere?



What bright star does Orion’s belt point towards?



What do fuzzy patches in the night sky often represent?



Name one of the days that the sun crosses the celestial equator?

On the equinoxes, 21st March , 21st September


What is the temperature of sunspots? How does this differ to the surrounding photosphere?

They are about 3,800 degrees Kelvin which is 2,000 degrees Kelvin less than the photosphere


What does the temperature of the chromosphere vary between? In general we say it is the higher end of this range, which is hotter the chromosphere or the photosphere ?

The chromosphere ranges between 4500 and 20000 degrees Kelvin, this means that despite being further away from the centre of the sun the chromosphere is hotter than the photosphere


What are meteoroids?

A small piece of rock that has not entered the earths atmosphere, possibly debris from comets or asteroids


What are meteors?

Small pieces of rock/dust sized particles left behind from meteoroids that are left in a trail in the meteoroids orbit. They burn up as they meet the earths atmosphere, also known as a shooting star


Why do meteor showers occur roughly annularly on Earth?

Because at the same point in orbit (same time of year) the Earth intercepts where the meteoroids orbit was and therefore all the meteors its left behind


What are meteorites?

A rock, stony or iron, that lands on Earth, most come from asteroids and some from the moon or mars. They form an impact crater


What is a micrometeorite?

An extremely small particle that is to small to burn up in the Earths atmosphere and can be collected at the poles, places there aren’t many humans


What is a fireball?

A meteor brighter than magnitude -5


What is a comet?

A dirty ice ball that we see when it is near its perihelion(closest point to the sun in its orbit) in its orbit, as it starts to sublime (goes from solid to gases). It has 2 tails, a nucleus and a coma


What is a coma of a comet?

The nebulous envelope (large cloud) around the nucleus of a comet which is made up of gas and dust


Who discovered Pluto? When?

Clyde Tombaugh 1930


Who discovered Ceres? When?

Giuseppe Piazza 1801


How was Pluto discovered?

Tombaugh noticed irregularities in Neptune’s and Uranus’ orbit so used repeated photographs and a blink comparator to find differences in the images, he found the differences to be caused by what at the time was the ninth planet, now known as a dwarf planet


How was Ceres discovered?

Using a large reflecting telescope and Bodes law to predict where more large sized objects (dwarf planets/ planets) were Ceres was located in the asteroid belt, although at the time it was believed to be a comet as it was moving quickly


Which is the largest dwarf plant? Which one is closest to the Sun (and Earth)?

Eris is the largest, closely followed by Pluto
Ceres is the closest to the sun and earth (located in the asteroid belt)


What are the 3 main ways of detecting exoplanets?

Astrometry, radial velocity and transit


How can astrometry be used to detect exoplanets?

Astrometry (parallax) is the science of precise measurements in a stars location in the sky, it detects slight but regular wobbles in a stars position. If it is detected, regularly over a long time of observing, it is likely to be an exoplanet. This is the oldest technique used.


How can transit be used to detect exoplanets?

It measures the small drop in magnitude as the planet transits in front of the star. It is a very minute change but noticeable after lots of observation.


How can radial velocity be used to detect exoplanets?

Radial velocity, redshift, can be used to detect how colour of objects differ as they move (whether they become more stretched out or shorter). This shows whether planets are orbiting as they move towards or away from us.


Where do long period comets originate from?

The Oort Cloud


Where do short period comets originate from?

The Kuiper belt