Grimes’ Secret Second Baby With Elon Musk Has A Name As Meaningful As X Æ A-12

The on-again couple secretly welcomed a baby girl named Exa Dark Sideræl via surrogate in late 2021.

NEW YORK, NY - MAY 07:  Grimes and Elon Musk attend "Heavenly Bodies: Fashion & the Catholic Imagina...
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Grimes’ upcoming album isn’t her only new arrival. Grimes secretly welcomed her second child with Elon Musk, a baby girl named Exa Dark Sideræl Musk, who her parents call “Y” to match their 22-month-old son X Æ A-12 Musk, or simply “X,” as revealed in a Vanity Fair cover story posted on March 10. They attempted to keep their newborn a secret, but Y revealed herself by crying during the in-person interview, and the writer couldn’t ignore it. “She’s a little colicky too,” Grimes said, reportedly laughing. “I don’t know. I don’t know what I was thinking.”

Y was born via surrogate in December 2021, which allowed Grimes and Musk to keep her a secret given that she was not pregnant herself, according to VF. And yes, this means they’re on again. In September, months before Y’s birth, the Tesla founder appeared to confirm their split, telling Page Six that they were “semi-separated” due to Grimes’ music career in Los Angeles and him moving Tesla and SpaceX’s headquarters to Austin. However, she has now relocated to Austin and is back together with Musk — but she’s still hesitant to label it.

“There’s no real word for it,” she explained. “I would probably refer to him as my boyfriend, but we’re very fluid. We live in separate houses. We’re best friends. We see each other all the time. We just have our own thing going on, and I don’t expect other people to understand it. ... This is the best it’s ever been. ... We just need to be free.” But after the article published on March 10, she tweeted, “Me and E have broken up again since the writing of this article haha.”

What Does Exa Dark Sideræl Mean?

Following the interview, Grimes revealed the meaning behind Y’s full name through text messages. Exa nods to the computing term exaFLOPS, which means the ability to perform “1 quintillion floating-point operations per second,” an achievement that Tesla’s supercomputer achieved in 2021. Meanwhile, Dark was simply inspired by “the unknown.” “People fear it but truly it’s the absence of photons,” she said. “Dark matter is the beautiful mystery of our universe.” Sideræl is pronounced “sigh-deer-ee-el” and is “a more elven” spelling of the word “sidereal,” which Grimes defines as “the true time of the universe, star time, deep space time, not our relative earth time.” It’s also a nod to her favorite Lord of the Rings character Galadriel.

Grimes called her daughter’s name “fire,” but she is prepared for Y to change it in the future and already has “dozens of ideas” should she choose to do so. Despite the thought that went into it, she was actually advocating for a different but equally epic name. “I was fighting for Odysseus Musk,” she writes. “A girl named Odysseus is my dream.” Luckily, she also said her and Musk want three or four children together, so there’s still time to make that happen.

How Is X Æ A-12 Doing?

Since his birth in May 2020, the couple has not hesitated from sharing the occasional photo of baby X Æ A-12, which is either pronounced “X-ash” or “X-A.I.” depending on who you ask. But don’t expect to see adorable snapshots of his sister. Scared off by multiple stalker incidents, one of which caused her to walk offstage during a 2016 show, Grimes is keeping her a little more shielded. “The best situation here is me training the girl and him [Musk] training the boy,” she said.