locating stars

Locating StarsPart 2

What are Constellations?

constellation is a group or clusters of stars that make an imaginary shape in the night sky.constellations are formed of bright stars which appear close to each other on the sky, but are really apart in space;constellations are arbitrary groupings of stars that have been constructed so as to assist in the location and identification of stars.

Traditional Constellations

refers to a pattern that is formed when imaginary lines are drawn in between stars close in proximity, forming an image.are patterns that appear identical to objects

Modern Constellation

are based on grid segments on the celestial sphere and are not

based on patterns.

An Asterism- is a more recognizable part of the larger constellation.Example: The Big Dipper is a part of Ursa Major, the Big Bear, and the Little Dipper is a part of Ursa Minor, the Little Bear.

Are Constellation Real or Not?

Astronomers: Constellations are not real. They are totally imaginary things

that farmers and astronomers have made up over the past 6,000 years

(and probably even more.)

Where did the Constellations come

from?

• Claudius Ptolemy- defined 48 lists of constellations in the 2nd century in his book entitled “ALMAGEST”.

• Johann Bayer- in his “Uranometria”

(1603) added 12 constellations from expedition to S-Hemisphere.

• Jakob Bartch(1624)-added 3 constellations.

• Johannes Hevelius- added 9 southern constellations in his “Firmamentum Sobiescianum sive Uranographia”.

• Nicholas Louis de Lacaille- added 14 constellations in 1763.

• John Flamsteed(1929) and Johan Elert Bode(1801)- produced other elegant star atlases.

• Mid-1800’s –Ptolemy’s largest constellation “Argo Navis”, has been divided into “carina”, “puppis’, and “vela”

• In 1922 the International Astronomical Union recognized 88 constellations based on the 48 listed by Ptolemy in his Almagest in the 2nd century and other astronomers.

Two Divisions of Constellation

Circumpolar Constellationare those that, from the viewer’s latitude, never set.circumpolar stars or constellations daily traces circles around the north celestial pole without setting or dipping below the horizon. They move in a counterclockwise direction.are those that are close enough to the North Celestial Pole that they remain above the horizon all the time as the sky turns.are always above the horizon, even in the daytime and visible at all seasons.

Examples: 1. Camelopardalis, 2. Cassiopeia, 3. Cepheus, 4. Draco, 5. Ursa Major and 6. Ursa Minor.

Seasonal Constellationare the remaining non-circumpolar constellations that are visible at the observer’s latitude.These constellations will rise and set as the earth turns.They appear in the sky during reasonable evening hours only at certain times of the year.

Examples: are the zodiac (Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius and Pisces).

Summer Constellations

Constellations around the Summer Triangle

1. Cygnus (with the bright star Deneb)2. Lyra (with Vega)3. Aquila (with Altair)

Constellations in the Southern Sky

4. Scorpius (with Antares)5. Sagittarius (teapot)

Fall Constellations

1. Pegasus2. Andromeda( with M31, a galaxy

similar to our Milky Way)3. Perseus (partly circumpolar)

Winter ConstellationsAlong the Ecliptic1. Taurus2. GeminiEquatorial 3. Orion (with Betelgeuse, Rigel and the

“Great Nebula”)4. Canis Major (with Sirius)5. Canis Minor (with Procyon)The rest of the family6. Auriga (with Capella)

Spring Constellations

1. Bootes2. Leo3. Corona Borealis4. Hercules