“To Boldly Go: Symphony Meets Space” at 8 p.m. Friday at First Church in Cambridge, 11 Garden St., Harvard Square. Free, but it’s best to register to attend.

The Berklee Contemporary Symphony Orchestra celebrates science (it’s the 100-year anniversary of the publishing of Albert Einstein’s Theory of Relativity) and science fiction (it’s the 50-year anniversary of “Star Trek”) with composer Michael Giacchino’s rendition of “Star Trek: Into Darkness”; Holst’s “The Planets: Jupiter, the Bringer of Jollity”; and the premiere of “Gravity,” the winning selection in the orchestra’s student composition contest, by Christian Bloquert. Bonus: Compositions by Philip Glass, Claudio Ragazzi and Derek Hurst inspired by the music of David Bowie. Information is here.

Coach Fest from 3 p.m. to midnight Saturday at The Middle East Downstairs, 480 Massachusetts Ave., Central Square. Tickets for this all-ages show are $12 in advance or $15 at the door (and come with 25 percent off a meal at The Middle East).

There’s no theme to this 18-band, two-stage rock festival aside from the fact the performers have been chosen by the talent bookers Coach & Sons as great bands that provide solid entertainment and sound good together. Explore the talent – most local, some from as far as California and England – here: Save Ends; Posture & The Grizzly; Queen Moo; dæphne; halfsour; Bat House; Sports.; People Like You; Holy Pinto; Perspective, a lovely hand to hold; The Most (seen above); Prince Daddy & The Hyena; Just Friends; Lilith; Kitner; Fall Risk; NOX; and Bad Dreams. Information is here.

International Games Day from noon to 4 p.m. Saturday at the Cambridge library’s O’Connell Branch, 48 6th St., East Cambridge. Free.

Usually closed Saturdays, this library branch is opening just to take part in International Game Day – and that includes some brand-new games delivered by Central Square’s Pandemonium Books & Games (though players can bring their own boards, cards and so on too). Information is here. (Other kids stuff to know about: There’s another Kids Union Dance Party from 3 to 5:30 p.m. Saturday at Thunder Road, 379 Somerville Ave., Union Square, Somerville for $5 per kid, free for the adults; and the Kids Table open mic for young musicians, spoken-word poets or other performers from 8:30 to 10 p.m. Saturday at the Hotung Cafe, 44 Professors Row, Somerville.)

“Voices Against Injustice” poetry reading from 6:30 to 9 p.m. Saturday at Out of the Blue Art Gallery Too, 541 Massachusetts Ave., Central Square. Admission to this all-ages show is $5.

Outraged? The Liberation Poetry Collective of Boston is holding this event, with readings by 10 contributors to an upcoming anthology, to “remember that poetry does matter” and to speak “in protest against injustice and the current atmosphere of renewed hate in the U.S.” Expect to hear from Richard Cambridge; Neil Callendar; Everett Hoagland; Jill Netchinsky; Aldo Tambolini; Tontongi; Askia Toure; Ashley Rose Salomon; Tony Van Der Meer; and Brenda Walcott. Information is here.

A ton of art in Somerville on Saturday and Sunday, all free.

This weekend brings not just the 29th annual Brickbottom Open Studios from noon to 6 p.m. Saturday and Sunday at the Brickbottom Artists Buildings, 1 Fitchburg St., including free interactive installations and pop-up performances in the common areas; but a free, all-ages pop-up poster art show from noon to 5 p.m. Saturday at Union Press, 440 Somerville Ave.; the opening day of the 33-artist Somerville Local Arts Mall from 10 a.m. to 8 p.m. Sunday at 337 Somerville Ave., near Union Square; Trash Bash 2016, an annual recycled art show competition, from 2 to 8 p.m. Sunday at Aeronaut Brewing, 14 Tyler St., near Union Square; and the “BoXed” opening reception from 3 to 5 Sunday at The Nave Gallery, 155 Powderhouse Blvd., near Teele Square. The 29-artist show asks “What’s a box?” and “what constitutes, is kept out from, is constricted by, could be nurtured by, memorializes, questions, endangers, deconstructs, skirts the edges of, remains curious in, explodes from, revels in, is made less clear by, is made more sere by, starts the tears by, smarts and veers by and could election engineer via the nature of being boXed.” (Some may also want to stop by the Lesley Art Therapy Association’s Open Studio from 11 a.m. to 1 p.m. Saturday and Sunday at 33 Mellen St., in the Agassiz neighborhood between Harvard and Porter squares, where art supplies are available to encourage people in journaling and making art.)

Your choice of free classical or jazz concerts from 8 to 10 p.m. Sunday in Cambridge and Somerville.

The Harvard University Choir and Harvard Baroque Chamber Orchestra present Handel’s “L’Allegro, il Penseroso ed il Moderato” in the beautiful Sanders Theatre, 45 Quincy St., near Harvard Square. The work, an ode based on the poetry of John Milton, will be conducted by Nicholas McGegan with soloists Amanda Forsythe, Sherezade Panthaki, Aaron Sheehan and Sumner Thompson. Information is here.

Tufts Small Jazz Ensemble presents “Setting New Standards” in the Granoff Music Center at Tufts University, 20 Talbot Ave. at Tufts University (technically in Medford), which presents jazz interpretations of non-jazz material, including works by Lennon and McCartney, Jagger and Richards, Gamble and Huff and more. The ensemble is under the direction of Paul Ahlstrand. Information is here.

More things to consider this weekend: Saturday is Local Comic Book Shop Day, and every local comic book store is stocked with limited edition collectibles (and some may have free stuff and local artists on hand, such as “Below Zero” writer Josh Dahl at Comicazi in Somerville’s Davis Square); the “Twin Peaks” pilot gets a live soundtrack from Mike Sim, with an opening set by Les Chaises, from 8 to 10 p.m. Saturday at Industry Lab near Inman Square, for a $5 to $10 sliding-scale admission that includes coffee and doughnuts; Kenneth Lonergan’s “This Is Our Youth” is staged by the Strange News theater company at 8 p.m. Saturday and 7 p.m. Sunday at the Studio at 550 in Central Square with $12 admission; and there’s a Massmouth Story Slam with the theme “Wiggle Room” 7 to 9 p.m. Sunday at Passim in Harvard Square for $5 to $10 admission.