Winter begins at 10:39 p.m. Wednesday with the winter solstice.
The term solstice is used twice a year - around June 21 for the summer solstice, the longest day of the year and around Dec. 21 for the winter solstice, the shortest day of the year.
Actually, our day is defined for civil purposes as being 24 hours long, with each day having the same length as any other day.
When we use the term "day" with respect to the solstices, we mean the time of daylight from when the sun rises until it sets. Thus, the longest period of daylight is at the summer solstice, and the shortest period of daylight is at the winter solstice. The summer solstice is the official start of summer, and the winter solstice is the official start of winter. The solstices are reversed in the Southern Hemisphere.
The exact date of a solstice varies by a few days every year because our calendar has 365 days a year (or 366 days in a leap year), but the Earth actually takes 365.256 days to complete one orbit around the sun. This coupled with small variations in the daily rotation of the Earth and the slow wobble of the Earth's axis contributes to slightly changing solstice dates.
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To celebrate the winter solstice a day ahead, rise early on Tuesday morning and look at the eastern horizon from 6:15 to 6:45. The nearly 25-day-old moon will be a very thin crescent 30 degrees above the southeastern horizon. Just above the moon is Saturn to the left (north) and Spica, the brightest star in Virgo the Virgin, to the right (south).
If conditions are really good, you can catch the top part of Scorpius the Scorpion along the horizon with a special treat, Mercury, in the front part of Scorpius.
Four ways to celebrate the winter solstice
1. Sombra y luz: 14th Annual Winter Solstice Celebration
• When: 7:30 p.m. Friday through Sunday and Wednesday.
• Where: Zuzi, 738 N. Fifth Ave.
• Admission: $18 Friday through Sunday; $20 Wednesday.
• More: 629-0237, www.zuzimoveit.org The dance company celebrates the solstice with modern and aerial dance in a performance that includes the Zuzi Professional company, Apprentice Company, "Many Limbs" Youth Aerial Company and members of the annual community workshop. There will also be a silent auction that includes jewelry, concert tickets, wine baskets and more to benefit Zuzi.
2. Winter Solstice at Children's Museum Tucson
• When: 1-4 p.m. Saturday.
• Where: 200 S. Sixth Ave.
• Admission: $2.
• More: 792-9985. The Children's Museum Tucson is joined by Puppets Amongus, Planetary Science Institute, Planet Djembe and Cub Club Samba for an afternoon of art and music. There will be leaf weaving, snowflake making, a puppet show and more for families to celebrate the start of winter. There will also be "snow."
3. Sun-Day on the Solstice
• When: 11 a.m. Sunday.
• Where: Kitt Peak National Observatory, take Arizona 86 to Junction 386.
• Cost: $40; $25 ages 8-16.
• Reservations required: 318-8726 Discover more about the sun: what it is, how it works and how to safely observe it in action. The program features a tour of the world's largest solar telescope (McMath-Pierce Solar Telescope), including direct observation of the sun. Also expect hands-on activities and the chance to become a human sundial.
4. Winter Solstice Party at Sky Bar
• When: 6 p.m. to midnight Wednesday.
• Where: 536 N. Fourth Ave.
• More: www.skybartucson.com Sky Bar, a self-described "solar powered cafe by day, astronomy bar by night," celebrates celestial events, such as major meteor showers, throughout the year. The Winter Solstice Party starts Wednesday during open mic with host D.J. Odious and includes drink specials.
Contact Tim Hunter at skyspy@azstarnet.com
