This year’s National Cheeseburger Day is interplanetary, thanks to Habit Burger & Grill.

The holiday takes place Wednesday, Sept. 18, prompting several restaurant promotions.

The most unusual comes from Habit, which sent a Double Charburger to space last week and offers photos, flight data and a declaration by the Planetary Society to prove it.

The launch was in Sandy Valley, a remote part of San Bernardino County near the Nevada border.

To be specific, the Irvine-based chain booked a flight on Sent into Space, a business that sends high-altitude balloons into the upper stratosphere for marketing campaigns and other reasons. Habit’s mission took place last week in advance of National Cheeseburger Day, according to a news release.

The launch was in Sandy Valley, a remote part of San Bernardino County near the Nevada border, the news release said. The burger reached a maximum altitude of 19.8 miles.

The flight also celebrates Habit taking first place in a fast food poll by USA Today 10Best Reader’s Choice Awards in July. The chain wanted to be above the competition, literally.

Here are some of the more earthbound offers that restaurant chains have announced on their websites or in social media and news releases. Participation may vary. Check with your local restaurants. All specials are available on Wednesday, Sept. 18 only, unless noted otherwise.

Applebee’s: The Classic Bacon Cheeseburger, Classic Cheeseburger and Classic Burger will sell for $8.99 with a side of fries. applebees.com

Bar Louie: Louie’s Choice Cheeseburgers are available with fries or tots for $9.95 11 a.m.-3 p.m. at participating locations. barlouie.com

Del Taco: There’s a buy-one-get-one offer on Double Del Cheeseburgers for Del Yeah! Rewards members. deltaco.com

Farmer Boys: The Big Cheese will sell for $4 each. The offer is limited to two burgers per person. farmerboys.com

Habit Burger & Grill: In addition to the space stunt, Habit is offering new members of its CharClub loyalty program a free Double Char with a minimum $5 purchase when they register for the CharClub, according to the news release. habitburger.com

McDonald’s: App users can get Double Cheeseburgers for 50 cents. mcdonalds.com

Red Robin: Customers can get a Gourmet Cheeseburger with a bottomless side for $10 Sept. 17-19, two days longer than its current Tuesday discount. redrobin.com

Rock & Brews: Ultimate and Oklahoma Smash Burger sell for $7.99. rockandbrews.com

Smashburger: Classic Singles will sell for $5 at participating locations. To order online, use the code CLASSIC24. Any purchase on that date will generate a coupon 50% off a burger or sandwich on a future visit. smashburger.com