Here's an introduction to the acts appearing Sunday, July 20 at Top of the Park — the Ann Arbor Summer Festival's free, outdoor component, held outside the Rackham Building, on East Washington Street at Ingalls Mall. And don't forget the Top of the Park Photo Contest, presented by AnnArbor.com for the festival.

Activities begin at 4 p.m. with the first edition of Acoustic Cafe Live @ Top of the Park, featuring a surprise guest. The KidZone Tent is open from 5-8 p.m., and Body Masterpiece will offer extreme face painting during the same hours.

The evening's other main attractions:

Tsars Rackham Stage, 5 p.m.

The Tsars recreate a musical era that never existed. A Land That Time Passed Over where Henry Mancini and Ennio Morricone mingled with the go-go surf beatnik scene. Where Dick Dale recorded a version of “Haitian Fight Song.” In their world, the influence of the exotic is not subordinated into the idea of kitsch. The Tsars have invented a musical vocabulary that draws from hipster popular culture, Surf, Tiki and exotic themes that combine with a Burroughs-esque self-conscious world-weariness. Elements of rock, jazz and whatever else the band has absorbed from being raised by the television set and the wolves of a lifetime of playing music come spilling back out in sometimes startling forms.

Performing since: 2008 Home base: Ann Arbor Style of music: Surf/Spy/Lounge Members: Brent Truex, guitar and vocals; Jamie Nielsen, keys and vocals; Jerry Hancock, bass; Ahvram Novetsky, drums. Pre-show ritual: Explain Lucy. Favorite road food: Free hot dogs Desert island disc: Project Pimiento "Magical Moods of the Theremin" Best thing about Ann Arbor: Squirrels More info: Website | MySpace | Facebook

Listen to Tsars "Mudslide" (MP3).

Jill Jack Band Rackham Stage, 6:30 p.m.

Jill Jack has a genre-blending style of folk, rock, country and Americana that reaches out and connects with the audience wherever she goes. Jill has received a total of 24 Detroit Music Awards across three different genres (Acoustic/Folk, Country, and Pop/Rock) for vocalist, songwriter, album, and artist. She and her band will be performing songs off her newest CD, "Songwriter Sessions."

Performing since: 1995 Home base: Ferndale Style of music: Americana Members: Ron Pangborn, Dale Grisa, Nolan Mendenhall and Billy Brandt Pre-show ritual: Prayer given by drummer Favorite road food: Heath bars after a really good show Desert island disc: Bob Marley "Legend: The Best Of" Best thing about Ann Arbor: The feeling of true community involvement Genre: Americana, folk, pop, country

More info: Website | MySpace | Facebook | Twitter

Listen to Jill Jack "Drink the Dust" (MP3).

JJ Grey & Mofro Rackham Stage, 8 p.m.

From gritty funk and juke joint romps, to contemplative country soul and blistering rockers, Grey’s music is in a class by itself, at once contemporary and classic. Now, with his latest release, “Orange Blossoms”, JJ Grey will bring his singular musical vision and hip-shaking, soulful live show to Ann Arbor, showing how his songs speak to people from all over and just how far-reaching his Southern roots can spread.

Genre: Country, Rock, Americana, Festival debut

More info: Website | MySpace | Facebook | Twitter

Listen to JJ Grey & Mofro "Everything Good Is Bad" (MP3).

JJ Grey & Mofro performing "The Sweetest Thing" live earlier this month:

Movie: "Star Trek" (2009) Ingalls Mall, 10 p.m.

The first Top of the Park free outdoor movie offering of the year is the well-regarded 2009 version of "Star Trek," directed by J.J. Abrams. A young space crew takes the maiden voyage of the starship Enterprise and ends up fighting an evil being's mission of vengeance.