chapter 2 constellations - ddtwo
TRANSCRIPT
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
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
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?
• 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)
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• 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.
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• 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 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
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.
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.
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
• 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?
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.
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.