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My Top 20 Guideposts in the Sky

Number

Common
Name

Constellation

Apparent
Magnitude

Spectral
Type

Luminosity
(Sun = 1)

Distance
(Light Years)

Radial
Velocity
(km / sec)

1 Sirius Canis Major -1.46 A1 26 8.7 -8
2 Canopus Carina -0.72 F0 15,000 310 +21
3 Alpha
Centauri
Centaurus -0.04 G2 1.7 4.3 -22
4 Arcturus Boötis 0.00 K2 115 36 -5
5 Vega Lyra 0.03 A0 52 25 -14
6 Capella Auriga 0.08 G8 F0 90 70 43 +30
7 Rigel Orion 0.12 B8 60,000 910 +21
8 Procyon Canis Minor 0.38 F5 7 11.4 -3
9 Achernar Eridanus 0.46 B5 400 85 +19
10 Betelgeux Orion 0.0 – 0.9 M2 105,000 v 640 +21
11 Agena Centaurus 0.61 B1 10,000 460 -11
12 Altair Aquila 0.77 A7 10 16.6 -26
13 Acrux Crux Australis 0.83 B1 3,200 360 -11
14 Aldebaran Taurus 0.85 K5 120 68 +54
15 Antares Scorpius 0.96 M1 7,500 330 -3
16 Spica Virgo 0.98 B1 2,100 260 +1
17 Pollux Gemini 1.14 K0 60 36 +3
18 Fomalhaut Piscis Australis 1.16 A3 13 22 +7
19 Deneb Cygnus 1.25 A2 70,000 1,800 -5
20 Becrux Crux Australis 1.25 B0 8,200 425 +20

Explanation

Number

This is a list of the 20 brightest stars as seen from the Earth (not including the Sun). The stars are numbered from 1 to 20 in sequence.

Common Name

This is the name by which the star is commonly known. The names are Greek, Latin or Arabic. This web site is based in London: stars not visible from London are in red.

Some examples of the names: Deneb is Latin for tail (because it marks the tail of The Swan – Cygnus); Antares is Greek for rival of Mars (because of its red colour); Aldebaran is Arabic for eye of the bull (because it marks the eye of The Bull – Taurus).

Constellation

A constellation is a star group (as seen from Earth) that the star is a part of. Constellations are human inventions. The stars in them appear in the same part of the sky but are, in fact, at different distances from us and not related to each other. Different cultures use different constellations. For more, read Astronomy and Astrology.

In the West, there are 88 recognised constellations; 48 of these date from Roman times and are known as the Classical Constellations. These include the 12 Zodiac constellations through which the Sun, Moon and planets always pass through. Constellations are always known by their Latin names.

Some examples: Canis Major means The Great Dog; Orion is The Hunter; Crux Australis means The Southern Cross.

Constellations are used by astronomers for convenience. We say that Sirius is in Canis Major rather than give its celestial coordinates.

Apparent Magnitude

Apparent Magnitude tells how bright the star is as seen from the Earth. The magnitude scale was devised by the Ancient Greeks. The brightest stars were called First Magnitude, the next brightest were called Second Magnitude, etc.

In modern times, the scale has been defined mathematically. A star of magnitude 1 is about 2.5 times brighter than a star of magnitude 2 which in turn is 2.5 times brighter than a star of magnitude 3. The brighter a star, the smaller its magnitude. Many stars are brighter than first magnitude. Some stars are so bright they have negative magnitudes. On this scale, Jupiter has a magnitude (at its brightest) of -2.6, Venus is at -4.4 and the Sun -27. The faintest stars visible to the naked eye are sixth magnitude. Pluto has a magnitude of +14, far too faint to be visible without a powerful telescope.

In the table it can be seen that Betelgeux varies its magnitude – some stars are variable in brightness.

The brightness of a star as seen from Earth depends on its intrinsic luminosity and its distance from Earth. A dim star may appear bright because it is close while a luminous star may appear faint because it is far away. This is why we say Apparent Magnitude.

Spectral Type

When starlight is passed through a prism, it splits into its constituent colours, like a rainbow. This is called the star’s Spectrum. Stellar spectra are crossed by dark lines. These lines give astronomers a lot of information about the star: temperature, luminosity, radius, magnetic properties, movement. Read The Electromagnetic Spectrum for more on spectra.

The Morgan-Keenan spectral classification

The Morgan-Keenan spectral classification (Photo credit: Wikipedia)

Stellar spectra are classified into types. These types are given letters. The spectral type series is a temperature series. Moving from the hottest stars to the coolest, the series of letters runs O, B, A, F, G, K, M.

Each spectral type is subdivided into ten numbers. For example, A0, A1, A2, up to A9. A0 is hotter than A1. The table below gives more information.

Spectral
Type

Colour

Surface
Temperature
(°C)

O

Blue >30,000

B

Blue-White 20,000

A

White 10,000

F

Yellow-White 7,000

G

Yellow 6,000

K

Orange 4,500

M

Red 3,000

Our Sun is a star of Spectral Type G2 with a surface temperature of around 6,000°C.

Luminosity

This tells us how much more energy and light the star gives off compared with the Sun. This is how bright the star really is once distance has been taken into account. There is a huge variety in the luminosity of the stars. At one extreme, the star Alpha Centauri is 1.7 times more luminous than the Sun. At the other extreme, Canopus is 15,000 times more luminous than our Sun.

Luminosity can be measured indirectly by combining the apparent brightness of a star with its distance. It can also sometimes be measured directly from the spectrum.

Distance

The distance of a star is given in Light Years. This is the distance covered by a light beam in one year. Light travels at 300,000 km per second (186,000 miles per second). In one year a beam of light will travel 9.4 million million km (5.9 million million miles). This enormous distance is a Light Year.

Many stellar distances can be measured directly by trigonometry. As the Earth moves around the Sun, the star appears to shift its position against more distant stars. This effect is called parallax. It is a tiny effect but can be measured. The amount of the parallax depends on the diameter of the Earth’s orbit around the Sun (just under 300 million km or 186 million miles) and the distance to the star. A star with a paralax of 1 second of arc (written 1″) is said to be at a distace of 1 Parsec. 1 Parsec is equal to 3.26 Light Years.

Other stars can have their luminosity measured by their spectra or by other properties. When this is compared to their apparent brightness, a distance can be calculated.

For more on astronomical distances look at The Scale Of The Universe.

Radial Velocity

This the velocity of the star relative to the Sun. Negative velocities denote a star moving towards the Solar System. Positive velocities are for stars moving away from us.

Radial velocity is easily measured by looking at the star’s spectrum. The lines on the spectrum are shifted to the blue end if the star is moving towards us (the so-called blue shift) and to the red end if the star is moving away from us (red shift). The amount of this shift depends on the relative velocity between us and the star.

Credits: http://www.krysstal.com/brightest.html

(heavenswithlamps.wordpress.com)

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Constellations: Official List

The Constellations Table :A complete table with information about all the 88 Constellations as defined by the I.A.U. ( International Astronomical Union ). Abbreviations, Genitive and Latin Names, English Names and more.FIELD LIST

ABBREV : IAU abbreviation
CONSTELLATION : latin name
GENITIVE : latin genitive ( possessive )
ENGLISH NAME : english translation
AREA : constellation size or area, in square degrees
HEM : position in the celestial sphere :
NH – northern celestial hemisphere – declination between 0° and +90°
SH – southern celestial hemisphere – declination between 0° and – 90°
ALPHA STAR : proper name of the alpha star.

ALPHABETICAL ORDER

Cosmobrain’s Constellation Table

No. Abbrev. Constellation Genitive English Name

Area

Hem.

Alpha Star

1

And

Andromeda Andromedae Andromeda

722

NH

Alpheratz

2

Ant

Antlia Antliae Air Pump

239

SH

3

Aps

Apus Apodis Bird of Paradise

206

SH

4

Aqr

Aquarius Aquarii Water Carrier

980

SH

Sadalmelik

5

Aql

Aquila Aquilae Eagle

652

NH-SH

Altair

6

Ara

Ara Arae Altar

237

SH

7

Ari

Aries Arietis Ram

441

NH

Hamal

8

Aur

Auriga Aurigae Charioteer

657

NH

Capella

9

Boo

Bootes Bootis Herdsman

907

NH

Arcturus

10

Cae

Caelum Caeli Chisel

125

SH

11

Cam

Camelopardalis Camelopardalis Giraffe

757

NH

12

Cnc

Cancer Cancri Crab

506

NH

Acubens

13

CVn

Canes Venatici Canun Venaticorum Hunting Dogs

465

NH

Cor Caroli

14

CMa

Canis Major Canis Majoris Big Dog

380

SH

Sirius

15

CMi

Canis Minor Canis Minoris Little Dog

183

NH

Procyon

16

Cap

Capricornus Capricorni Goat ( Capricorn )

414

SH

Algedi

17

Car

Carina Carinae Keel

494

SH

Canopus

18

Cas

Cassiopeia Cassiopeiae Cassiopeia

598

NH

Schedar

19

Cen

Centaurus Centauri Centaur

1060

SH

Rigil Kentaurus

20

Cep

Cepheus Cephei Cepheus

588

SH

Alderamin

21

Cet

Cetus Ceti Whale

1231

SH

Menkar

22

Cha

Chamaleon Chamaleontis Chameleon

132

SH

23

Cir

Circinus Circini Compasses

93

SH

24

Col

Columba Columbae Dove

270

SH

Phact

25

Com

Coma Berenices Comae Berenices Berenice’s Hair

386

NH

Diadem

26

CrA

Corona Australis Coronae Australis Southern Crown

128

SH

27

CrB

Corona Borealis Coronae Borealis Northern Crown

179

NH

Alphecca

28

Crv

Corvus Corvi Crow

184

SH

Alchiba

29

Crt

Crater Crateris Cup

282

SH

Alkes

30

Cru

Crux Crucis Southern Cross

68

SH

Acrux

31

Cyg

Cygnus Cygni Swan

804

NH

Deneb

32

Del

Delphinus Delphini Dolphin

189

NH

Sualocin

33

Dor

Dorado Doradus Goldfish

179

SH

34

Dra

Draco Draconis Dragon

1083

NH

Thuban

35

Equ

Equuleus Equulei Little Horse

72

NH

Kitalpha

36

Eri

Eridanus Eridani River

1138

SH

Achernar

37

For

Fornax Fornacis Furnace

398

SH

38

Gem

Gemini Geminorum Twins

514

NH

Castor

39

Gru

Grus Gruis Crane

366

SH

Al Na’ir

40

Her

Hercules Herculis Hercules

1225

NH

Rasalgethi

41

Hor

Horologium Horologii Clock

249

SH

42

Hya

Hydra Hydrae Hydra ( Sea Serpent )

1303

SH

Alphard

43

Hyi

Hydrus Hydri Water Serpen ( male )

243

SH

44

Ind

Indus Indi Indian

294

SH

45

Lac

Lacerta Lacertae Lizard

201

NH

46

Leo

Leo Leonis Lion

947

NH

Regulus

47

LMi

Leo Minor Leonis Minoris Smaller Lion

232

NH

48

Lep

Lepus Leporis Hare

290

SH

Arneb

49

Lib

Libra Librae Balance

538

SH

Zubenelgenubi

50

Lup

Lupus Lupi Wolf

334

SH

Men

51

Lyn

Lynx Lyncis Lynx

545

NH

52

Lyr

Lyra Lyrae Lyre

286

NH

Vega

53

Men

Mensa Mensae Table

153

SH

54

Mic

Microscopium Microscopii Microscope

210

SH

55

Mon

Monoceros Monocerotis Unicorn

482

SH

56

Mus

Musca Muscae Fly

138

SH

57

Nor

Norma Normae Square

165

SH

58

Oct

Octans Octantis Octant

291

SH

59

Oph

Ophiucus Ophiuchi Serpent Holder

948

NH-SH

Rasalhague

60

Ori

Orion Orionis Orion

594

NH-SH

Betelgeuse

61

Pav

Pavo Pavonis Peacock

378

SH

Peacock

62

Peg

Pegasus Pegasi Winged Horse

1121

NH

Markab

63

Per

Perseus Persei Perseus

615

NH

Mirfak

64

Phe

Phoenix Phoenicis Phoenix

469

SH

Ankaa

65

Pic

Pictor Pictoris Easel

247

SH

66

Psc

Pisces Piscium Fishes

889

NH

Alrischa

67

PsA

Pisces Austrinus Pisces Austrini Southern Fish

245

SH

Fomalhaut

68

Pup

Puppis Puppis Stern

673

SH

69

Pyx

Pyxis Pyxidis Compass

221

SH

70

Ret

Reticulum Reticuli Reticle

114

SH

71

Sge

Sagitta Sagittae Arrow

80

NH

72

Sgr

Sagittarius Sagittarii Archer

867

SH

Rukbat

73

Sco

Scorpius Scorpii Scorpion

497

SH

Antares

74

Scl

Sculptor Sculptoris Sculptor

475

SH

75

Sct

Scutum Scuti Shield

109

SH

76

Ser

Serpens Serpentis Serpent

637

NH-SH

Unuck al Hai

77

Sex

Sextans Sextantis Sextant

314

SH

78

Tau

Taurus Tauri Bull

797

NH

Aldebaran

79

Tel

Telescopium Telescopii Telescope

252

SH

80

Tri

Triangulum Trianguli Triangle

132

NH

Ras al Mothallah

81

TrA

Triangulum Australe Trianguli Australis Southern Triangle

110

SH

Atria

82

Tuc

Tucana Tucanae Toucan

295

SH

83

UMa

Ursa Major Ursae Majoris Great Bear

1280

NH

Dubhe

84

UMi

Ursa Minor Ursae Minoris Little Bear

256

NH

Polaris

85

Vel

Vela Velorum Sails

500

SH

86

Vir

Virgo Virginis Virgin

1294

NH-SH

Spica

87

Vol

Volans Volantis Flying Fish

141

SH

88

Vul

Vulpecula Vulpeculae Fox

268

NH

BY EDUARDO SOARES

©Cosmobrain.com 2001 – All Rights Reserved.

Credits : http://www.cosmobrain.com/cosmobrain/res/constellations.html

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