Chapter 2 Constellations - DDTwo

Chapter 2

Constellations

Key Terms

Almagest

Andromeda Galaxy

Asterism

Betelgeuse

Cannis Major

Cassiopeia

Constellation

Dark cloud constellations

Gemini

Lascaux

Leo

Ophiuchus

Orion

Orion Nebula

Pleiades

Polaris

Sirius

Taurus

Ursa Major

Ursa Minor

Zodiac

ConstellationsConstellations are visual grouping of stars.

ConstellationsThe constellations that we see on the celestial sphere

are not physical groupings.

ConstellationsIn most cases the stars in constellations are each very

different distances from us, and only appear to be

grouped because they lie in approximately the same

direction.

ConstellationsThe constellation is a commemoration and not a true

representation of the person or object.

Constellations• Ancient times - named after gods, heroes, and

animals.

• Each culture has its own set of constellations.

Constellations• We are familiar with the constellations that we see

regularly in the night sky - a distinctive pattern of

stars.

• They do not usually have any real link to each other

• Each star is often at a different distance from the

Earth.

Constellations• We are familiar with the constellations that we see

regularly in the night sky - a distinctive pattern of

stars.

• They do not usually have any real link to each other

• Each star is often at a different distance from the

Earth.

Constellations• We are familiar with the constellations that we see

regularly in the night sky - a distinctive pattern of

stars.

• They do not usually have any real link to each other

• Each star is often at a different distance from the

Earth.

Constellations• The constellations would look very different if the

Earth was somewhere else.

• In fact many of the stars that we see in a constellation

are far away from each other.

ConstellationsAndromeda

Antlia

Apus

Aquarius

Aquila

Ara

Aries

Auriga

Boötes

Caelum

Camelopardalis

Cancer

Canes Venatici

Canis Major

Canis Minor

Capricornus

Carina

Cassiopeia

Centaurus

Cepheus

Cetus

Chamaeleon

Circinus

Columba

Coma Berenices

Corona Australis

Corona Borealis

Corvus

Crater

Crux

Cygnus

Delphinus

Dorado

Draco

Equuleus

Eridanus

Fornax

Gemini

Grus

Hercules

Horologium

Hydra

Hydrus

Indus

Lacerta

Leo

Leo Minor

Lepus

Libra

Lupus

Lynx

Lyra

Mensa

Microscopium

Monoceros

Musca

Norma

Octans

Ophiuchus

Orion

Modern times - 88

constellations with well

defined boundaries.

Constellations

Pavo

Pegasus

Perseus

Phoenix

Pictor

Pisces

Piscis

Austrinus

Puppis

Pyxis

Reticulum

Sagitta

Sagittarius

Scorpius

Sculptor

Scutum

Serpens

Sextans

Taurus

Telescopium

Triangulum

Triangulum

Australe

Tucana

Ursa Major

Ursa Minor

Vela

Virgo

Volans

Vulpecula

Constellations• Prior to 1922 there were as many as 137 constellations with

many more asterisms.

• In 1922, the IAU divided the celestial sphere into 88 official

constellations.

• This system created a division of the celestial sphere into 88

well defined areas.

Constellations

• Prior to 1922 there

were as many as 137

constellations with

many more asterisms.

• In 1922, the IAU

divided the celestial

sphere into 88 official

constellations.

• This system created a

division of the celestial

sphere into 88 well

defined areas.

ConstellationsOut of the 88 modern constellations, 36 lie predominantly in the

northern sky, and the other 52 predominantly in the southern.

Constellations

• The modern 88

constellations are

based on the 48 listed

by Ptolemy in his work

Almagest.

• Thirty of those listed

by Ptolemy date back

to at least the Late

Bronze Age.

Constellations

The only one of

Ptolemy’s

constellations that was

rejected by the IAU

was the Argo Navis, a

large constellation in

the southern

hemisphere

Constellations

• The Argo Navis was

divided into four

constellations:

• Carina (keel)

• Puppis (poop deck)

• Vela (sails)

• Pyxis (compass)

• All four are accepted

by the IAU.

In antiquity, the Pyxis was part of the Argo’s mast, so

there is some contention as it (the compass) being part of

the original constellation.

• Some of patterns appear to exactly like the object it

represents.

• Asterism is a star-pattern that is not officially classed

as a constellation.

Constellation

The Big Dipper

is not a

constellation

• Some of patterns appear to exactly like the object it

represents.

• Asterism is a star-pattern that is not officially classed

as a constellation.

Constellation

Ursa Major –

The Big Bear

The classical -- "ancient" -- constellations that

populate our sky began in the lands of the middle east

thousands of years ago, their origins largely lost to

time.

Constellation

Constellations

•They passed

through the hands

of the ancient

Greeks, who

overlaid them with

their legends and

codified them in

story and verse.

•The Romans

“Latinized’ their

names.

When were the first constellations recorded?• Archaeological studies have identified possible

astronomical markings painted on the walls in the cave

system at Lascaux in southern France.

• Our ancestors may have recorded their view of the

night sky on the walls of their cave some 16,500 to

17,300 years ago.

Ancient Constellations

Ancient Constellations

Ancient Constellations

Ancient Constellations

Ancient Constellations

Ancient Constellations

Ancient Constellations

Dark Cloud Constellations• Not all

constellations use

stars to create the

image.

• Some cultures

create dark cloud

constellations.

• In Australia, the

Aborigines use

the dark cloud

nebula Coalsack

and the Milkyway

to create "Emu in

the sky”.

Dark Cloud Constellations

Members of the Inca

civilization identified

various dark areas or

dark nebulae in the

Milky Way as animals,

and associated their

appearance with the

seasonal rains.

Finding Constellations• During the pre-industrialized period, people saw the

Milky Way on a nightly basis.

• Today, city lights (light pollution) makes it practically

impossible to find the Milky Way.

• Many of the stars in constellations are faint in the

scattered light of urban areas.

Finding ConstellationsRather than detailing each of the 88 constellations, we

will focus on 8 of the most easily located constellations

in the sky above The Fort.

Ursa Major (AKA The Big Dipper)

• As mentioned earlier,

the Big Dipper is not a

constellation, but is an

asterism.

• Be that as it may, the

Big Dipper is probably

one of the first objects in

the sky that we learn to

find and identify.

• The Big Dipper is made

of 7 stars.…or is it?

Ursa Major (AKA The Big Dipper)

• To the keen unaided eye, two stars can be seen, the

brighter Mizar, and a fainter nearby star, Alcor.

• They are separated by about 12 minutes of arc, and

being able to detect the two as separate is considered

a test of good eyesight

Ursa Major (AKA The Big Dipper)

• Starting with Ursa Major, it is easy to find Ursa Minor

(the little dipper).

• The two end stars of the cup portion of the Big Dipper

align with Polaris (the North Star).

Ursa Minor (AKA The Little Dipper)

• The stars of the Little Dipper are not as bright at those

found in the Big Dipper.

• The handle of the Little Dipper arches in the opposite

direction than the Big Dipper’s handle.

Ursa Minor (AKA The Little Dipper)

Ursa Minor (AKA The Little Dipper)

Ursa Minor (AKA The Little Dipper)

Ursa Minor (AKA The Little Dipper)

Ursa Minor (AKA The Little Dipper)

Ursa Minor (AKA The Little Dipper)

Cassiopeia

• In alignment with Big Bear and the Little Bear, we will find

Cassiopeia

• She is opposite the Big Bear

• Imagined a line from the visible double of the Big Bear

(Mizar and Alcor) passing through Polaris

• Cassiopeia’s form is peculiar since according to the time

of the year in which we observe

• it will have form of the letters E, M, or W

Cassiopeia

Cassiopeia

Cassiopeia• The Andromeda Galaxy is the farthest object most of

us will ever see with the naked eye.

• The Andromeda Galaxy is similar to our Milky Way in

size and structure; both are spiral galaxies containing

several hundreds of billions of stars.

Cassiopeia

• To find the Andromeda Galaxy, start with the familiar

W of Cassiopeia.

• Use the right side of Cassiopeia as an "arrow" to point

you to the galaxy, located one outstretched fist to its

lower right.

• If you have difficulty seeing Andromeda with your

naked eye, try binoculars.

Cassiopeia

• To find the Andromeda Galaxy, start with the familiar

W of Cassiopeia.

• Use the right side of Cassiopeia as an "arrow" to point

you to the galaxy, located one outstretched fist to its

lower right.

• If you have difficulty seeing Andromeda with your

naked eye, try binoculars.

Leo• Going back to the Big Dipper/Bear, we can find

Leo, one of the constellations of the Zodiac.

• An imaginary line from the “cup” away from the

Little Dipper will terminate on Regulus.

• Leo is distinct in the backward question mark that

creates the head of the lion.

Leo

Leo

Leo

Orion

• Between the months of

November and February,

Orion is very easy to

locate

• It contains two very bright

stars.

• The reddish star

Betelguese, is a

supergiant with a

mass 19 times

greater than the Sun.

• Rigel a blue

supergiant is 117,000

times brighter than our

Sun.

Orion

Orion

Orion

Orion

Orion

Orion

OrionHorsehead Nebula

OrionHorsehead Nebula

Orion• The Orion Nebula

(AKA M42, or

NGC 1976) is a

nebula situated in

Orion's Belt.

• It is one of the

brightest nebulae,

and is visible to

the naked eye in

the night sky.

NGC = New General

Catalog

Orion

• Forming Orion’s right

shoulder (the left-

side of Orion) is

Betelgeuse.

• It is the eighth

brightest star in the

night sky and

second brightest star

in the constellation

of Orion.

Orion• Forming Orion’s right shoulder (the left-side of

Orion) is Betelgeuse.

• It is the eighth brightest star in the night sky and

second brightest star in the constellation of Orion.

Orion• Forming Orion’s right shoulder (the left-side of

Orion) is Betelgeuse.

• It is the eighth brightest star in the night sky and

second brightest star in the constellation of Orion.

Orion

• Betelgeuse is

already old for its

size class and is

expected to explode

relatively soon.

• The supernova

would outshine the

Moon in the night

sky and become

easily visible during

the day.

Canis Major

• Orion’s belt points to the

brightest star in our sky.

Sirius is in the constellation

of Canis Major or Big Dog.

• Its name is Latin for greater

dog, and is commonly

represented as one of the

hunting hounds following

Orion.

Canis Major

Canis Major is one of the 88 modern constellations,

and was included in the 2nd-century astronomer

Ptolemy's 48 constellations.

Canis Major

• The star Sirius is white color with blue reflections.

• It is sometimes seen to iridescence, greenish or

reddish reflections.

• This only happens when it is low on the horizon;

this is purely an atmospheric phenomenon.

Canis Major

• The star Sirius is white color with blue reflections.

• It is sometimes seen to iridescence, greenish or

reddish reflections.

• This only happens when it is low on the horizon;

this is purely an atmospheric phenomenon.

Canis Major

• The star Sirius is white color with blue reflections.

• It is sometimes seen to iridescence, greenish or

reddish reflections; but this only happens when it

is low on the horizon; this is purely an

atmospheric phenomenon.

Visible Light X-Ray

Canis Major

• Following in the

opposite

direction from

Sirius Major, the

line terminates

on the star

Aldebaran.

• This star forms

the eye of the

Bull or Taurus.

Taurus

Taurus

The ecliptic passes

between Aldebaran

and the Pleiades.

Taurus

Taurus

Taurus

TaurusThe Pleiades, or Seven Sisters (M45), is an open star

cluster containing middle-aged hot B-type stars located in

the constellation of Taurus.

Taurus• The Pleiades is one of the easiest star clusters to see

with the naked eye.

• The cluster is dominated by hot blue and extremely

luminous stars that have formed within the last 100

million years.

Taurus

Taurus

Gemini

• Back to Orion, a line

beginning with Rigel,

passing through

Betelgeuse, will

terminate with Castor.

• Castor and Pollux form

the twin heads of

Gemini.

Taurus

Constellations

Constellations

Gemini

Gemini

Orion and Company

Orion and Company

The ZodiacIn astronomy, the zodiacal constellations are a

convenient way of marking the ecliptic.

Sign Constellation

Name English Tropical zodiac NameIAU constellation

boundaries

Solar stay

(days)

Aries The Ram 20 March – 20 April Aries 18 April – 13 May 25.5

Taurus The Bull 20 April – 21 May Taurus 13 May – 21 June 38.2

Gemini The Twins 21 May – 21 June Gemini 21 June – 20 July 29.3

Cancer The Crab 21 June – 22 July Cancer 20 July – 10 August 21.1

Leo The Lion 22 July – 23 August Leo10 August –

16 September36.9

Virgo The Virgin23 August –

23 SeptemberVirgo

16 September –

30 October44.5

Libra The Scales23 September –

23 OctoberLibra

30 October –

23 November21.1

Scorpio The Scorpion23 October –

22 NovemberScorpius

23 November –

29 November8.4

Serpentarius The Snake Handler Ophiuchus29 November –

17 December18.4

SagittariusCentaur The

Archer

22 November –

22 DecemberSagittarius

17 December –

20 January33.6

Capricorn The Sea Goat22 December –

20 JanuaryCapricornus

21 January –

16 February27.4

AquariusThe Water

Bearer20 January – 18 February Aquarius

16 February –

11 March23.9

Pisces The Fish 18 February – 20 March Pisces 11 March – 18 April 37.7

The Zodiac

The Zodiac

The Zodiac

• Astronomers

still use tropical

coordinates for

predicting the

positions of the

planets.

• Currently, Mars

& Saturn are in

Sagittarius.

The Zodiac

In Astrology, if you are a Leo, then the Sun was in

the constellation Leo at the time of your birth.

The Age of Aquarius?

• Astrologers maintain

that an astrological age

is a product of the

earth's slow

precessional rotation

and lasts for 2,160

years, on average

• 26,000-year period of

precession / 12 zodiac

signs = 2,160 years).

The Age of Aquarius?

• There are various

methods of calculating

the length of an

astrological age.

• Astrologers believe

that an astrological age

affects humanity,

possibly by influencing

the rise and fall of

civilizations or cultural

tendencies.

The Age of Aquarius?

The Age of Aquarius?

Age of Cancer: 8640 to 6480 BC

Age of Gemini: 6480 to 4320 BC

Age of Taurus: 4320 TO 2160 BC

Age of Aries: 2160 to 0 BC

Age of Pisces: 0 BC to 2160

Age of Aquarius: 2160 to 4320

The Age of Aquarius?

Age of Pisces: 0 BC to 2160

Pisces rules: Transcendence, Spirituality, Contact with

Other Worlds, Fear, Prophets and Prophecy,

Dissolution, Dreams, Illusion, and Lack of Direction.

Age of Aquarius: 2160 to 4320

Aquarius rules: Brotherhood, Utopia, Genius and

Science, Immortality, Hopes Dreams and Wishes,

Revolution, Electricity.

Google Sky Map

• Google Sky Map is a free

a free app for an Android

Phone.

• It uses GPS, compass,

and motion sensors to

locate celestial objects.

• Apple has a similar app,

SkyView.

Apple Night Sky

Similar to Google Sky Map

Stellarium

Stellarium is a free open source planetarium for

your computer. It shows a realistic sky in 3D, just

like what you see with the naked eye, binoculars or

a telescope.

Constellations

It’s

Over!