WHERE: AT EXPLORIT Science Center, 3141 5th Street, Davis.

Constellations!
Saturday, April 30, 2005
From 7:00 - 9:00p.m. at Explorit, 3141 5th Street, Davis
Hosts: Vinita & Calvin Domier (530) 756-0191, vcdomier@yahoo.com

Join us Saturday evening, April 30th, at 7:00 p.m., when we will discuss the different constellations in the sky. We will also look at the stars in the night sky, weather permitting.

This program is free and available for all ages.

Astronomers have calculated that there are about 70 sextillion -that's 7 followed by 22 zeros- stars in our universe. In other words, there are more stars than there are grains of sand in all the Earth's beaches and deserts combined!

The stars are grouped together into galaxies. Our Sun is part of the Milky Way Galaxy, which contains about 40 billion stars. The Milky Way (along with 23 other galaxies) is part of the Local Group cluster, which is part of the Virgo Supercluster (containing approx. 2000 galaxies). There are millions of galaxies and thousands of clusters of galaxies cataloged.

The stars in the sky are at different distances from Earth and are traveling in different directions. The simplest way to represent them in charts and planispheres is to assume Earth is surrounded by a celestial sphere that spins on its axis and has north and south poles. The stars are represented on the inside surface of this imaginary sphere, and hence appear to be at the same distance from Earth.

The imaginary celestial sphere is divided into 88 non-overlapping sections, or constellations (recognized by the International Astronomical Union in 1933). All stars, nebulas, galaxies, etc. are assigned to the constellation in whose boundaries they appear to be in, with the brightest stars acting like landmarks in the sky to guide observers.

Each of the 88 constellations has an internationally accepted name. Many of them were named by our ancestors thousands of years ago with a few named within the last 200 years. People mentally connected the brighter stars in each constellation, imagining them to outline mythical people and creatures, animals, and objects. For example, Ursa Major is named after the big bear shape the ancients imagined. In some instances, parts of constellations (known as asterisms) were also named, like the Big Dipper in the Ursa Major constellation.

12 of the 88 constellations constitute the Zodiac. These constellations are in a band that lies on the ecliptic, which is near the equator of the celestial sphere. Ecliptic is the projection of the Earth's path around the Sun on the celestial sphere. The Sun (and the Moon, and the planets) appears to move in the sky in this narrow band, moving through the 12 Zodiac constellations in a year.

Depending on the location of the observer on Earth, some constellations are always visible, some are visible seasonally, and some are never visible. The latitude here in Davis is 40degreesN. The sky appears to pivot around the North Celestial Pole, which is 40degreesN above the horizon. The stars in circumpolar constellations, within 40degrees of Polaris (the North Star), will never set. Stars within 40degrees of the Southern Celestial Pole will never be above the horizon for Davis stargazers. All other stars, south of 40degreesN and north of 40degreesS, will be visible to Davis observers for part of the year only.

SPRING NIGHT SKY
Jupiter (-2.3, Virgo) Opposition: Apr. 3.
Jupiter rises at sunset and sets at sunrise.
Saturn (+0.1, Gemini) rises at midnight.
Mars (+0.8, Cap/Aqr) rises before dawn.
Venus Superior Conjunction: 30 Mar. Venus is thus not visible
Vernal (Spring) Equinox: Mar. 20.
Partial Solar Eclipse: April 8. (It is
visible in Southeastern U.S., not in CA.)
Lyrids Meteor Shower: peaks Apr. 22.
Eta Aquardis Meteor Shower: May 5.
Moon's Phases: New Moon: Apr. 8/May 8, First Quarter: Apr. 16/May 16, Full Moon: Apr. 24/May 23, Last Quarter: Apr. 30/May 30.

Contact Vinita Domier at vcdomier@yahoo.com to receive these bulletins via e-mail.

The Astronomy Club is for everyone - adults, children, knowledgeable or ignorant. Come to listen, look and learn, or to share your expertise or experience.