Topic 6

Question 1

What is the appearance of a star in the night sky?

Answer 1

Appears to be a point of light in the sky that scintillates

Question 2

What are the two types of double star and why are they different?

Answer 2

Binary star & optical binary.

Optical binary stars do not share a common centre to orbit.

Question 3

What is a binary star?

Answer 3

2 + stars that shave a gravitational bond and orbit around a common centre - they appear to be two closely positioned points of light

Question 4

What is an optical binary?

Answer 4

Two stars that appear close, and to be binary but are unrelated by gravitational attraction

Question 5

What is a constellation?

Answer 5

A group of stars that appear to make a pattern in the sky.

We see different throughout the ones year due to our rotation and axial tilt.

Question 6

What is an asterism?

Answer 6

A pattern of stars that may or may not be linked to a constellation

• the plough is in ursa major
• Deneb is in Cygnus

Question 7

What is the difference between a constellation and an asterism

Answer 7

They’re both patterns of stars. However, constellations are a group of 88 recognised official patterns. Asterisms are smaller patterns within constellations, nothing official.

The asterism The big dipper / the plough is a part of the constellation called ursa Major

Question 8

What is a star cluster?

Answer 8

Groups of stars which are gravitationally bound.

Question 9

What are galaxies?

Answer 9

Gravitationally bound system of stars, stellar remnants, interstellar gas, dust & dark matter

Question 10

What is a nebulae?

Answer 10

Cloud of gas & dust in outer space, visible in the night sky as either an indistract bright patch or a silhouette against other luminous matter

Question 11

Appearance of a planet in the night sky

Answer 11

Appear as a point of light in the sky that does not scintillate due to now close they are relative to Earth

Question 12

What is a comet?

Answer 12

Balls of frozen gases, rock, and dust that orbit the sun.
- point of light clearly noticeable over a short period of time
- vast trails of ice & dust over a large portion of sky

Question 13

What is a meteor?

Answer 13

Small, rocky, irregular lumps of debris in the solar system

• often originating from the dust trails of comets, forming a group called meteoroid streams and are the source of meteor showers (emerging from the radiant)
• many meteoroids enter the atmosphere and friction causes them to burn up and produce a streak of light (meteor/shooting star)
• streak of light lasts a matter of seconds

Question 14

What is aurorae?

Answer 14

Bands of coloured light in the sky, curtains of light
- when the solar wind interacts with the atmosphere

Question 15

What is a supernovae?

Answer 15

Burst of extremely bright light in the sky, very rare

• it is the death of a massive star

Question 16

How does an artificial satellite appear?

Answer 16

Slow moving, very faint objects orbiting in a polar orbit, viewable on the median

Question 17

How do aircraft appear?

Answer 17

Multiple bright white & red lights slowly moving over the sky

Question 18

How does the milky way appear?

Answer 18

Faint grey band in the sky

Question 19

What is light pollution and how does it affect viewing?

Answer 19

Optical light from human sources.

It reduces contrast in the sky and ruins vision at night.

Question 20

What things can obstruct viewing at night?

Answer 20

-Air pollution
-Saharan dust
-clouds
-mountains (landscape)
-other celestial bodies

can reduce clarity

Question 21

What is The celestial sphere?

Answer 21

The imaginery sphere around Earth.

Question 22

What is right ascension and where is it measured from?

Answer 22

Longitude of a star from the first point of Ares ( imagine a clock)

Question 23

What is RA measured in?

Answer 23

Hours, minutes, seconds

Question 24

How to and right ascension?

Answer 24

Find degrees that an object is east of the F.P.A.
360/x = y
24/y = RA

Question 25

Find the right ascension of a Star that is 90 degrees East

Answer 25

360/90 = 4 24/4 = 6hr RA

Question 26

What is declination and where is it measured from?

Answer 26

Latitude of a star from the celestial equator measured in degrees, arc minutes’, and arc seconds” -arc minute is 1/60 degree -arc second is 1/60 of an arc minute -3600” in 1 degree

Question 27

What position in the sky is a star with the declination +45 from the equator

Answer 27

45 degrees

Question 28

What is the altitude of an object?

Answer 28

How high an object is in the sky from the horizon -measured in degrees -90 degrees = zenith

Question 29

What is the azimuth of an object

Answer 29

How eastward ain object is by due north (bearing) -measured in degrees -90 degrees = due east

Question 30

Which altitude does the latitude of an observer equal?

Answer 30

North celestial pole

Question 31

What is the meridian

Answer 31

Imagine line passing through the north Pole, south pole, and the observer

Question 32

What is the local sidereal time?

Answer 32

The LST of an observer is the RA of a star on the observer's median. if the RA us 5hr35min when it crosses the observer’s meridian then the LST is 05:35

Question 33

True or false: a person on a meridian in London will see the sun culminate earlier than someone in Bristol (2 degrees west)?

Answer 33

True

Question 34

What is hour angle and how is it measured?

Answer 34

Hour angle is the angle between the meridian of the observer and the meridian of the star - this line is called the houn circle. - measured in hours, minutes, seconds

Question 35

What is the hour angle of a Star if an observer is looking at a star due west of their position, at 9pm The Star transits the observers meridian at 11:30pm

Answer 35

2hr30min HA

Question 36

What direction do we calculate hour angle? How far is a Star 1 hour East of the meridian(2hr30min HA)

Answer 36

23 hours, Westwards

Question 37

What is the formula for Hour angle

Answer 37

HA=LST-RA

Question 38

The Star Betelgeuse rises from London at 20:03 on the 23rd November. What time will it rise on the 30th November (stars rise approx. 4 mins earlier each day)

Answer 38

23/11 to 30/11 = 7 days 7x4=28 20:03- 00:28=19:35 Betelgeuse rise at 19:35 on the 30th November

Question 39

What are cardinal points

Answer 39

North, south, East, west on compass

Question 40

What is culmination?

Answer 40

Culmination is when a star reaches the observer’s meridian

Question 41

What is upper culmination? And what is lower culmination

Answer 41

- when a star is at its highest point in the sky - when a star is at its lowest point in the sky

Question 42

What is a circumpolar star?

Answer 42

A star that reaches both upper and lower culmination above the horizon

Question 43

What is co-declination? what is the formula?

Answer 43

The distance between the north celestial pole and a star, Co-dec = 90-declination

Question 44

What is a seasonal star?

Answer 44

Stars seems at various points in the year due to axial tilt and orbit of Earth

Question 45

How do you determine whether a Star is circumpolar or not?

Answer 45

90 degrees- declination < latitude of observer

Question 46

What is co-latitude and How do you work it out?

Answer 46

The distance between the latitude of the observer and the celestial pole Co-dec = 90- latitude of star

Question 47

Betelgeuse has a right ascension of 05hr55min. It culminates at 02:03 on the 6th January. Rigel culminates at 01:23 on the 6th January, what is Rigel's right ascension?

Answer 47

01:23 minus 02:23=difference of -40 minutes 05:55-40 minutes = 05:15min= right ascension of Rigel

Question 48

Betelgeuse has a right ascension of 05hr55min. It culminates at 02:03 on the 6th January. Rigel culminates at 01:23 on the 6th January. On the same day Sirius has a right ascension of 06h45m What time does it culminate?

Answer 48

06:45 - 0:55 = difference of +50 minutes 62:03 +50 minutes =02:53

Question 49

The Star Betelgeuse rises from London at 20:03 on the 23rd November. A person 3° west sees the star culminate at What time?

Answer 49

1° West = difference of +4 minutes 3° = 12 minutes Star culminates at 20:03+0:12=20:15

Question 50

As saying Polaris has a declination of 90° north At what angle in the Sky would it be visible from these locations? A) Beijing 40°N b) Bombay 19°N C) Wellington 41°S

Answer 50

A) 40° B) 19° C) it is not visible as it would be 41° below the horizon when culminating

Question 51

A star seen from London (51°) culminates at 30° above the horizon . What is the star's declination

Answer 51

90-51=39 30-39 =9°N

Question 52

A star culminates at 50° it has a declination of +20° - What is the latitude from where it's observed?

Answer 52

The altitude is equal to the declination + (90 ° -latitude) the latitude is the declination - altitude +90° 20°-50° +90° =+60°

Question 53

A person on the Tropic of Cancer measures the angle of the Sun at midday on different days. What angle is it at on these dates? a) March 21st b) June 21st c) september 21st d) december 21sr

Answer 53

a)66.5 degrees b) 47 degrees c) 66.5 degrees d) 90 degrees

Question 54

It is midday on December 21st. What angle is the Sun in the sky at these locations? A) tropic of cancer ( 23.5° North) B) Sydney ( 34° South) C) South Pole ( 90° South) D) London (51° North) Bear in mind the sun has a declination of -23.5 (South) above the equator. It is at the zenith from the tropic of capricorn

Answer 54

A) 90- 23.5 = 43 degrees B) 90- (34 + 23.5)= 79.5 degrees C)90-(90+23.5)=23.5 degrees D)90-(51-23.5)=15.5 degrees

Question 55

Geoff and Billy observe the Star Capella at different places. Geoff sees Capella Cross the meridian at 19:00. Billy is 3° East of Geoff. What time does Billy see Capella Cross the median. A year later the same happens, only Billy sees Capella 10 minutes later than Geoff. How far has Billy gone?

Answer 55

1° = 4 minute difference. 3°=12 minutes, East means the number is negative so sees it sooner 19:00 - 12 minutes = 18:48 4 min difference= 1 degrees, 10 minutes = 2.5° difference. Seeing the star later means he is now west so he is 2.5° west of Geoff.

Question 56

When does upper culmination take place?

Answer 56

Right acsencion= LST