Astronomy Club 2013 Constellations & Annual Rotation

Objective: To describe the motions of the stars, sky, and sun through out the year.

Setting the Stage: Question: What does the earth do once a day? Rotates once on its axis – Sidereal Day = 23h 56m 4s Question: What else happens during this time? The Earth moves about the Sun – Solar Day Solar time is also known as “local” time. Question: What are our clocks based on: Sidereal or Solar Time? Solar – 24 hrs Through these two motions, the sun and stars seem to move about the heavens each day. Based on the solar day, stars rise 4 mins earlier each day. Why? Due to the difference in Sidereal and Solar days Remember: Sidereal day = 23h 56m 4s, & Solar day= 24 hours Starting PointSidereal DaySolar Day

Application: Let’s look at a practical example: a a.We start both our Sidereal Clock and our Solar Clock at 6:36p, December 1, Image a. b.The next night the Earth completes 1 rotation at 6:32p per the Sidereal clock (~4 mins shorter than the 24-hour Solar Clock) b Look at the position of Rigel, Mintaka, and Betelgeuse in image b. a How do they differ from image a? c.Now, we wait until our Solar clock reaches 24hrs. c a.Look at the image c on the right. What is different? b b.How do the positions of Rigel, Mintaka, and Betelgeuse differ from image b? a bc

3 Day example: Betelgeuse & Rigel rise 4 mins early each day

1 Month example: Betelgeuse & Rigel rise 4 mins early each day 1 Month apart

Apply what you know: You know, stars rise 4 mins earlier each day due to the difference in Sidereal & Solar Time You know, There are 31 days between December 1 st and January 1 st. Therefore, at what time will Rigel rise on January 1 st in order to be in the same position as it was, relative to you at Duffield Sports center, when the date was December 1 st ? 1 Month apart

Aires: “The Ram” Represents the Ram’s horn Has several meteor showers associated with it Gamma Arietis (ƴ) is a triple star system Look at the map….what else is there?

Pisces: “The Fish” The Vernal Equinox is located here (when the Sun moves to the northern hemisphere across the equator) Contains two galaxies colliding Has ten stars with known exoplanets The Piscids meteor shower is here Look at the map….what else is there?

Aquarius: “The Water-Bearer” Beta Aquarii is a Supergiant Star Contains the Saturn Nebula and the Helix Nebula Has 7 stars with known exoplanets There are 4 meteor showers in Aquarius Look at the map….what else is there?

Capricornus: “The Goat” Has 3 stars with known exoplanets There are 5 meteor showers here Deneb Algedi (Delta Capricorni δ) is a 4 star system 39 LY away Algiedi (Alpha Capricorni α) is an optical binary star Look at the map….what else is there?

Sagittarius: “The Archer” Summer Constellation Looks like a Tea Pot (Asterism: Teapot) Contains the center of the Milky Way Has a radio source known as Sagittarius A* (thought to be the black hole at the center of the galaxy) Has 22 stars with confirmed exoplanets Look at the map….what else is there? QUESTION: WHY do you think there are so many Messier objects near here?

Scorpius: “The Scorpion” Pre-dates the Greeks. One of the oldest constellations known. Dates back to the Sumerians Has 13 stars with known exoplanets Has Antares, one of the sky’s brightest stars. A Red Supergiant it makes up the “heart” of the scorpion 2 meteor showers associated here Look at the map….what else is there?

Libra: “The Weighing Scales” Contains Methuselah, currently the OLDEST known star in the universe (See red circle to the right). Estimated at 14B years old 3 stars with known exoplanets There is one meteor shower here Look at the map….what else is there?

Virgo: “The Virgin” Home to the Autumn Equinox 20 stars with known exoplanets Two meteor showers Look at the map….what else is there?

Leo: “The Lion” 11 Stars with known exoplanets 2 meteor showers located here Alpha Leonis is a 4 star system Look at the map….what else is there?

Cancer: “The Crab” 2 stars with known exoplanets 1 meteor shower Look at the map….what else is there?

Gemini: “The Twins” Twins are: Castor & Pollux Several stars with known exoplanets 2 meteor showers Castor is a quad-binary star with a rotation period of 467 years Pollux has an exoplanet 2.3 times as large as Jupiter and is 33 LY away Look at the map….what else is there?

Taurus: “The Bull” Contains two star clusters: Pleiades & Hyades The Crab Nebula is here 5 stars with known exoplanets 2 meteor showers Aldebaran: Orange Supergiant. Seen in the Hyades star cluster but actually 90LY closer to earth. Hyades star cluster is 150LY away