The moon may turn blood red tonight, perhaps an eerie sign heralding the arrival of Halloween on Sunday.

It's not that an evil spell has been cast on our celestial neighbor. It's a remarkable astronomical event that can be observed virtually any place the sky is clear in North America.

A total eclipse of the moon, lasting about 1 hour, 22 minutes, is expected to create a spooky spectacle.

The eclipse is caused by the shadow of the Earth falling upon the full moon. Some sunlight will pass through Earth's atmosphere and could illuminate the moon in a reddish hue. The partial phase of the eclipse comes first, when Earth's dark shadow touches the moon at 9:14 p.m., though there may be some visible shading as much as a half hour before.

Totality begins at 10:23 and lasts until 11:45 p.m. The partial eclipse ends at 12:54 a.m. and the final shading of the moon may last another 30 minutes. Unlike an eclipse of the sun, a lunar eclipse is safe to observe.

The public is invited to watch the eclipse with members of the Amateur Astronomers Association of Pittsburgh tonight at Wagman Observatory in Deer Lakes Park, Frazer. For directions or more information, call 724-224-2510 or visit www.3ap.org.

Halloween festivities get under way as early as tomorrow. Community events include the following:

Braddock -- Trick or treating, 6 to 8 p.m. Sunday.

Braddock Hills -- Trick or treating, 6 to 8 p.m. Sunday.

Chalfant -- Trick or treating, 6 to 8 p.m. Sunday.

Churchill -- Trick or treating, 6 to 8 p.m. Sunday.

Delmont -- Trick or treating, 6 to 8 p.m. Sunday.

Derry Borough -- All events are Saturday. A parade will be 1:30 p.m. at Derry Area High School stadium sponsored by DA Business & Professional Association. Trick or treating follows from 3 to 7:30 p.m.

Derry Township -- Trick or treating, 2 to 5 p.m. Saturday.

East Huntingdon -- Trick or treating, 2 to 4 p.m. Sunday.

East McKeesport -- All events are Saturday. A parade will be at 4 p.m., and children should meet at the post office. Trick or treating follows from 6 to 8 p.m.

East Pittsburgh -- Trick or treating, 6 to 8 p.m. Sunday.

Edgewood -- Haunted house, Koenig Field House, Greendale and Race streets, Friday and Saturday evenings. Trick or treating, 6 to 8 p.m. Sunday.

Export -- Parade, 7 p.m. Friday at fire hall. Trick or treating, 6 to 8 p.m. Saturday.

Forest Hills -- Trick or treating, 6 to 8 p.m. Sunday.

Greensburg -- Parade, 5:30 p.m. at Lynch Field on Saturday. Trick or treating, 6 to 8 p.m.

Hempfield -- Trick or treating, 6 to 8 p.m. Sunday.

Hunker -- Parade, 6 p.m. Friday. Lineup begins at 5:30 p.m. at park, proceeds to fire hall, with judging and treat bags, trick or treating after that till 9 p.m.

Irwin -- All events are Saturday. Parade at 3 p.m. through downtown, followed by a Monster Bash in Irwin Park and the Little Knights Kingdom playground. Trick or treating, 6 to 8 p.m.

Jeannette -- Parade, 7 tonight. Trick or treating, 6 to 8 p.m. tomorrow.

Latrobe -- Parade, 4 p.m. Saturday, followed by trick or treating from 5 to 8 p.m.

Madison -- Parade, noon Saturday at the ballfield. Trick or treating follows.

Manor -- Parade, 1 p.m. Saturday, Manor Lower Park. Trick or treating, 6 to 8 p.m. Sunday.

McKeesport -- Trick or treating, 6 to 8 p.m. Sunday.

Monroeville -- Trick or treating, 5:30 to 7 p.m. Sunday.

Mount Pleasant Borough -- Parade at 7 tonight, Main Street. Trick or treating, 2 to 4 p.m. Sunday.

Mount Pleasant Township -- All events on Sunday. Trick or treating, 2 to 4 p.m. Halloween party at 5 p.m., Calumet Volunteer Fire Department.

Murrysville -- Trick or treating, 6 to 8 p.m. Sunday.

New Stanton -- Trick or treating, 5 to 7 p.m. Saturday. Judging, parade, bonfire and treats, 7:30 p.m. in New Stanton Park.

North Braddock -- Trick or treating, 2 to 4 p.m. Sunday.

North Huntingdon -- Haunted Halloween trail, 6 to 9 p.m. Saturday, Indian Lake Park. Activities include carved pumpkin contest, costumes, treats. Trick or treating, 6 to 8 p.m. Sunday.

North Irwin -- Trick or treating, 6 to 8 p.m. Saturday.

North Versailles -- Party, 7 p.m. Friday at community center. Trick or treating, 6 to 8 p.m. Saturday.

Oakmont -- Parade forms at 9:45 a.m. Saturday at Washington and Isabella. Trick or treating 6 to 8 p.m. Sunday.

Penn Hills -- Trick or treating, 6 to 8 p.m. Sunday. The Department of Parks and Rec- reation is providing Halloween treat bags and activity books to children ages 2 to 12 to help them think safety when trick or treating this year. The treat bags are made of a reflective material. The items are free and can be picked up at the municipal building on Frankstown Road on a first- come, first-served basis during of- fice hours, 8 a.m. to 4:30 p.m. through Friday. For information, call the department at 412-798-2147.

Penn Borough -- Trick or treating, 6 to 8 p.m. Sunday.

Penn Township -- Parade, 5- 7:30 p.m. Friday, Penn Middle School track. Judging closed at 5:45 p.m. Children from Penn Borough and Trafford also welcome to participate. Trick or treating, 6 to 8 p.m. Sunday.

Pitcairn -- Parade, 1 p.m. Sat- urday in front of elementary school. Harvest festival for children 12 and younger follows at park. Trick or treating 5:30 to 7 p.m. Sunday.

Plum -- Trick or treating, 6 to 8 p.m. Sunday.

Rankin -- Trick or treating, 6 to 8 p.m. Sunday,

Salem -- Trick or treating, 6 to 8 p.m. Sunday.

Scottdale -- Trick or treating, 2 to 4 p.m. Sunday.

Sewickley Township -- All events on Saturday. Halloween parade 1:30 p.m. at Herminie Veterans of Foreign Wars. Trick or treating, 2 to 5 p.m.

South Greensburg -- Parade, 5 p.m. Saturday in front of American Legion, followed by trick or treating from 6 to 8 p.m.

South Versailles -- Trick or treating, 6 to 8 p.m. Sunday.

Southwest Greensburg -- All events Saturday. Parade at Amos Hutchinson School, with registration starting at noon. Trick or treating, 6 to 8 p.m.

Swissvale -- Parade at noon Saturday on Roslyn Street, with hayride at Dickson Field. Trick or treating, 6 to 8 p.m. Sunday.

Trafford -- All events on Sunday. Parade starts at 1 p.m. at the fire company, followed by a puppet show and luncheon at American Legion. Trick or treating, 6 to 8 p.m.

Turtle Creek -- Trick or treating, 2 to 4 p.m. Saturday.

Unity -- Trick or treating, 4 to 8 p.m. Sunday.

Verona -- Parade at 11 a.m. Saturday at Borough Building East Railroad. Trick or treating, 6 to 8 p.m. Sunday.

Versailles -- Parade lineup at 1:45 p.m. Sunday at fire hall on Third Street. Trick or treating, 6 to 8 p.m.

West Newton -- Parade at 1 p.m. Sunday at the Lions Club, Pittsburgh Street. Trick or treating follows through 7 p.m.

White Oak -- Parade lineup 12:30 p.m. Saturday, with 1 p.m. start at Sampson Mills Presbyterian Church. Trick or treating, 6 to 8 p.m. Sunday.

Wilkins -- Trick or treating, 6 to 8 p.m. Sunday.

Wilkinsburg -- Trick or treating, 5 to 8 p.m. Saturday.

Wilmerding -- All events on Sunday. Parade, hayride and costume judging, 1 to 5 p.m. at park in front of middle school. Trick or treating, 6 to 8 p.m.

Youngwood -- Parade, 7 p.m. today at Lincoln and Fourth. Trick or treating follows until 9 p.m.

Youngstown -- Parade, 6 p.m. today, starting at Sacred Heart Church parking lot. Trick or treating until 8 p.m.