topic 6

Question 1

what are constellation?

Answer 1

The night sky is divided into 88 different areas called constellations

Question 2

what is an asterism?

Answer 2

An asterism is a popular, unofficial pattern of bright stars that is generally easily identifiable as they do look like their name.
These are very useful in astronomy as they are often easy to recognise.

Question 3

what are examples of asterisms?

Answer 3

The Big Dipper/Plough is an asterism found in the constellation Ursa Major.

Question 4

what are Open clusters?

Answer 4

Open clusters are loosely bound groups of a few tens to a few hundred stars. They are found in spiral and irregular galaxies

Question 5

what is a Meteor?

Answer 5

A meteor is a streak of light in the sky caused by a meteoroid crashing through Earth’s atmosphere

Question 6

what is a shooting star?

Answer 6

A shooting star is really a small piece of rock or dust that hits Earth’s atmosphere from space. It moves so fast that it heats up and glows as it moves through the atmosphere. Shooting stars are actually what astronomers call meteors. Most meteors burn up in the atmosphere before they reach the ground.

Question 7

what is a comet?

Answer 7

A comet is a small, icy object that orbits the sun and has a long “tail” of gas. Some comets can be seen from Earth every few years, while others pass by once in a person’s lifetime. Comets are made of ice, dust, and tiny pieces of rock, but to people on Earth, they look like streaks or smudges across the night sky.

Question 8

what is a Supernova?

Answer 8

A supernova is a powerful and luminous explosion of a star. A supernova occurs during the last evolutionary stages of a massive star, or when a white dwarf is triggered into runaway nuclear fusion.

Question 9

what is a Planet?

Answer 9

A planet is a celestial body that it is in orbit around the Sun and has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic

Question 10

what are pointers?

Answer 10

Pointers are stars within asterisms that point towards less recognisable features.

Question 11

what is the celestial sphere?

Answer 11

The celestial sphere is an imaginary sphere extending from the surface of the earth, which we can “map” the night sky onto.

Question 12

what is the ecliptic?

Answer 12

The ecliptic is the path the sun takes from the viewpoint of the earth.

Question 13

what isThe celestial equator is inline with ?

Answer 13

The celestial equator is inline with the equator on the earth.

Question 14

what is the first point of aries?

Answer 14

The First point of Aries is where the celestial equator crosses the ecliptic.
The sun’s path crosses the celestial equator on the vernal (spring) equinox.

Question 15

what is The horizontal measurement is called within The Horizontal coordinate system

Answer 15

The horizontal measurement is called the azimuth. Click and drag on the horizon to change it.

Question 16

what is The vertical measurement is called within The Horizontal coordinate system

Answer 16

The vertical measurement is called the altitude

Question 17

what is the Azimuth?

Answer 17

Azimuth is an angle measured from due north, going eastward until the observer’s horizon aligns directly under the star. It spans from 0 to 360 degrees.

Question 18

what is altitude?

Answer 18

Altitude is the angle from the horizon upwards to the celestial object, ranging from 0 to 90 degrees. It corresponds to the observer’s latitude.

Question 19

why is the favourited amongst amateur astronomers.

Answer 19

The Horizontal coordinate system is simple to use which makes it a favourite amongst amateur astronomers. This is partially because it focuses on the observer.

Question 20

what is a zenith?

Answer 20

The highest point directly above an observer

Question 21

what is the equatorial coordinate system?

Answer 21

The height of the celestial objects are measured in declination in the same way as latitude (where + and – indicate N and S).

Question 22

how is a right ascension measured?

Answer 22

Right ascension is measured eastwards (anti-clockwise) from the point of Aries. This means it increases It is measured in hours and minutes where 1-hour equals 15o.

Question 23

what is Diurnal motion?

Answer 23

Diurnal motion is the daily motion of stars and other celestial bodies across the sky.

Question 24

what gives the stars and other celestial bodies apparent motion from east to west?

Answer 24

This motion is due to the Earth’s rotation from west to east, which causes celestial bodies to have an apparent motion from east to west.

Question 25

define culmination?

Answer 25

the instant at which a celestial object reaches its highest altitude above the horizon by crossing the observer’s meridian.

Question 26

what is The celestial meridian?

Answer 26

The celestial meridian is the line on the celestial sphere joining the observer’s zenith (the point directly overhead) with the north and south celestial poles

Question 27

what is a solar day?

Answer 27

A solar day is the time taken for the Sun to move from its highest point in the sky back to its highest point the following day. This is exactly 24 hours.

Question 28

what is a sideral day?

Answer 28

A sidereal day is the time it takes for the Earth to actually rotate once on its axis. A sidereal day is four minutes shorter than a solar day (23hrs and 56mins). It measures the rotation of Earth relative to the stars rather than the sun.The stars always appear at the same place in the sky at the same time each sidereal day.

Question 29

why is The sidereal day is shorter than the solar day?

Answer 29

The sidereal day is shorter than the solar day because as well as rotating on its axis, the Earth also orbits the Sun. In the time it takes the Earth to spin once about its axis, it also moves along its orbit by over 2.5 million km.Because Earth has moved, the sun will not appear in the same part of the sky at the end of that rotation.To end up facing the sun again, the Earth has to rotate for another 4 minutes.

Question 30

what is the local sideral time?

Answer 30

Local Sidereal midnight is defined to be when the first point of Aries passes directly overhead

Question 31

what is An object’s Hour Angle?

Answer 31

Hour angle is the time since the object last crossed the local meridian.

Question 32

what does The hour angle of an object represent?

Answer 32

The hour angle of an object represents its angular distance from the meridian, measured in hours where 1 hour equals 15 degrees. For example, an object with an hour angle of 2.5 hours crossed the meridian 2.5 hours ago and is currently located 37.5 degrees west of the meridian.

Question 33

1) what does the Negative Hour Angles signify
the Local Meridian.
2) what does An Hour Angle of zero indicate?
3) what does the positive hourl angle show

Answer 33

Negative Hour Angles signify the time remaining until the next transit across the Local Meridian
.
An Hour Angle of zero indicates that the object is presently on the Local Meridian.

Positive values tell us how long since it passed the local meridian

Question 34

how do you calculate the hour angle?

Answer 34

local sidereal time – right ascension (of the object)

Question 35

what is the polar distance?

Answer 35

Polar distance is the angular distance of the star from the celestial pole (sometimes called co-declination).

Question 36

how do you calculate the polar distance?

Answer 36

It is calculated by astronomers using:
Polar distance = 90o - declination
declination, in astronomy, the angular distance of a body north or south of the celestial equator.

Question 37

whats it called Where the star culminates in the celestial sphere?

Answer 37

Where the star culminates is called the upper transit

Question 38

The lowest point of the celestial sphere?

Answer 38

The lowest point is called the lower transit

Question 39

What is a circumpolar star?

Answer 39

For a star to be circumpolar its polar distance must be less than the altitude of the NCP.
90- angle of altitude of NCP
it has to be under 50 degrees

Question 40

what are the limiting factors of the visibility of the night sky?

Answer 40

Light pollution (sky glow and local glare)
Transparency of the atmosphere (dust particles in the air – can be removed by air)
Seeing conditions caused by turbulence in the air (I-V on the Antoniadi Scale)

Question 41

what are eye rods and cones?

Answer 41

Rod cells are one of the two types of photoreceptor cells located in the retina of the eye, the other being cone cells. Rod cells are highly sensitive to light and are primarily responsible for vision in dim or low-light conditions, such as night vision. They are distributed throughout the retina,

Question 42

what is averted vision?

Answer 42

Averted vision is a technique used in astronomy to observe faint objects, such as faint stars, galaxies, or nebulae, more effectively. Instead of looking directly at the object, the observer looks slightly to the side of it, using the peripheral vision

Question 43

how can we Improving our night vision in astronomy?

Answer 43

Dark Adaptation: Spend at least 20-30 minutes in a dark environment before observing to allow your eyes to adapt to low light conditions. Avoid exposure to bright lights during this time.
Red Light: Use a red flashlight or red headlamp instead of white light sources, as red light does not disrupt night vision as much. Red light allows you to see your charts, equipment, and surroundings without affecting your dark adaptation.
Averted Vision: As mentioned earlier, use averted vision to observe faint objects by looking slightly to the side of them rather than directly at them. This technique utilizes the more sensitive peripheral vision.