Earth Day events this weekend in Detroit

True spring weather is back this weekend after a wild week of sun and snow. • Here's how to be a good citizen and celebrate Earth Day this weekend: Plant trees: Arboretum Detroit is honoring the day with a tree planting event at Oxygen Alley on the east side. You'll dig holes, push wheelbarrows and spread wood chips to mulch the new trees. Free planetarium show: Up to 60 people can watch a planetarium show for free at Wayne State at 6pm tonight. • The planetarium is located...