Washington (AFP) - Is the dress black and blue, or white and gold?
That question is lighting up the Internet.
It all started when a Tumblr user with the handle 'swiked' uploaded a picture of a dress with the caption: "guys please help me - is this dress white and gold, or blue and black? Me and my friends can't agree..."
And then the Internet blew up.
The post went viral on Twitter, Facebook and other social media platforms, with users passionately split over what color the dress really is -- blue with black lace, or white with gold lace.
A BuzzFeed page devoted to the debate had more than 25 million views early Friday, with 72 percent of Internet users insisting the dress was white and gold, while 28 percent swore it was blue and black.
Even the glitterati weighed in.
"What color is that dress? I see white & gold. Kanye sees black & blue, who is color blind?" Kim Kardashian wrote on Twitter, on the debate raging in her household with rapper husband Kanye West.
"I don't understand this odd dress debate and I feel like it's a trick somehow," pop diva Taylor Swift wrote in a message retweeted more than 90,000 times.
"I'm confused and scared. PS it's OBVIOUSLY BLUE AND BLACK."
There may be a scientific explanation for all the madness.
According to British physicist Isaac Newton, color is not inherent to objects. Humans perceive the colors reflected on the surface of objects through light that hits the retina in the back of the eye.
Reena Garg, an assistant professor at the New York Eye and Ear Infirmary of Mount Sinai in New York, said the varied reactions can be explained by how we understand color, noting that the poorly exposed photograph was likely taken with a cell phone camera.
"If you see the dress as black and blue, you're probably seeing the photo as over-exposed, meaning there is too much light, so the colors in the dress appear darker to you after the retina has compensated," Garg told AFP.
"If you see the dress as white and gold, you're probably seeing the photo as under-exposed, meaning there is too little light and the colors in the dress appear lighter to you after the retina has compensated."
On Friday, after the Internet explosion, 'swiked' asked simply: "What have I done?"
Of course, there is an answer to it all.
A description on British manufacturer Roman Originals confirms that the dress is, in fact royal blue with lace, and sells for £50 ($77).