Looking for something to do with the kids this weekend? Hudson Valley families can get up close and personal with butterflies, meet Madeline, embark on a simulated space mission or learn about optical illusions. Get all of the details here.

Friday-Saturday: Meet Madeline in West Nyack

Ooh la la! Parents, get your cameras ready, because Madeline herself will make a special appearance at a Barnes and Noble story time. Meet the beloved character and take an imaginary journey to the old house in Paris at a reading of one of Ludwig Bemelmans’ charming tales about the little schoolgirl with the big sense of adventure.

When: 7 p.m. Friday, Sept. 14; 11 a.m. Saturday, Sept. 15

Info: Barnes and Noble, The Palisades Center, 4416 Palisades Center Dr., West Nyack; 845-348-4701; store-locator.barnesandnoble.com/store/2905; free

Saturday: "Majestic Monarch" event in Cornwall

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Do you know the monarch butterfly’s favorite food? Find out what it is and learn how to plant it to encourage the beneficial beauties to flutter into your own yard. Everyone age 5 and up is invited to learn about the winged creatures at a short presentation. After the presentation the group will take a guided hike in search of butterflies and caterpillars.

When: 10 a.m. Saturday, Sept. 15; rain date is 10 a.m. Sunday, Sept. 16

Info: Hudson Highlands Nature Museum’s Outdoor Discovery Center, Muser Drive across from 174 Angola Rd., Cornwall; 845-534-5506, ext. 204; www.hhnaturemuseum.org; $7 for adults, $5 for children; members pay $5 for adults, $3 for children

Sunday: "Return to the Moon" space mission in Airmont

Future astronauts can get a taste of space travel on this simulated mission to the moon. The young crew will attend a briefing session, then divide into teams such as Navigation, Communications and Medical, where they’ll work together on fun and challenging tasks to complete their mission. Teams trade places halfway through the program, so every young space adventurer gets a turn on the spacecraft and in the mission control room.

When: 2 p.m. Sunday, Sept. 16 (arrive at 1:45 p.m.)

Info: Town of Ramapo Challenger Learning Center, 225 Rte. 59, Airmont; 845-357-3416; www.lhvcc.com; $10 per person age 9 and up; $5 for seniors; $5 for kids under 9 (must be accompanied by a ticketed adult)

Sunday: "Where Science and Magic Collide" event in Yonkers

What’s an optical illusion? Climb aboard the Science Barge to find out during a fun introduction to perception puzzles. Use the scientific method to learn about symmetry, manipulation of perception and the connection between the eye and the mind at this week’s Art and Science Sundays workshop for ages 4 to 10.

When: 2 p.m. Sunday, Sept. 16

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Info: The Science Barge, 99 Dock St., Yonkers; 914-513-7354; www.groundworkhv.org/programs/science-barge/events-workshops; $3 suggested donation; free admission for kids 10 and under; $5 suggested supplies fee