Over the last 15 years, two of the world’s most high-profile CEOs, Elon Musk and Jeff Bezos, have been engaged in a simmering rivalry. The two execs have sparred over their respective space ambitions – Musk runs SpaceX, while Bezos owns Blue Origin – but it hasn’t stopped there: Musk has called out Bezos for running what he deemed a monopoly, and has called Bezos a copycat for his self-driving car interests. Musk and Bezos are two of the most powerful CEOs in the world. Bezos is currently the wealthiest living person and runs Amazon’s sprawling empire while also involving himself in Blue Origin’s quest to send people to the moon. Musk is a dual CEO, manning the ship at both Tesla and SpaceX. Over the years, their not-so-subtle rivalry has even given way to Twitter spats and name-calling. Now, Bezos is surpassing Musk in a major way: by heading to space himself. Bezos announced that he will be on Blue Origin’s first human space flight in July alongside his younger brother, Mark. Here’s how Musk’s and Bezos’ rivalry began – and everything that’s happened since. Move over, Mukesh Ambani: here’s how Indian billionaire Gautam Adani, Asia’s new second-richest man, spends his wealth Jeff Bezos in the early 2000s Back in the early 2000s, Jeff Bezos wasn’t yet the titan he is today. Bezos had launched Amazon five years prior , and the company had gone public in 1997. But Amazon wasn’t yet the powerhouse it would become. It was years before the company would launch Prime, start its own streaming service, or create its cloud infrastructure service, Amazon Web Services. But Bezos had always been interested in space. He told the Miami Herald in 1982, after he graduated high school as valedictorian, that he wanted to create outer space colonies for millions of people. As a result of that long-held interest in leaving Earth, Bezos launched Blue Origin in 2000, a new startup focused on human space flight. Elon Musk before Tesla Elon Musk, meanwhile, was already a millionaire several times over, but he hadn’t become CEO of Tesla yet. Around the time Bezos was launching Blue Origin, Musk had already sold Zip2, a startup he launched with his brother, Kimbal, to Compaq for roughly US$300 million. Musk was in the process of building PayPal, which would later be sold to eBay for US$1.5 billion. Musk made about US$160 million off the PayPal sale and used that money to launch SpaceX in 2002. “In the beginning, I actually wouldn’t even let my friends invest because everyone would lose their money,” Musk said during an interview at South by Southwest in 2018. “I thought I’d rather lose my own money.” The Musk-Bezos rivalry begins ... The Musk-Bezos rivalry appears to date back to 2004 when the two CEOs met for dinner. At that point, both Blue Origin and SpaceX were still in their infancy – neither company had completed any launches yet. But that didn’t stop a rivalry from heating up. When the two met to discuss their respective reusable rocket ambitions it apparently did not go well. “I actually did my best to give good advice, which he largely ignored,” Musk said after the meeting, according to Christian Davenport’s book The Space Barons . Earlier this year, Trung Phan, a writer for the business newsletter The Hustle, tweeted a photo of Musk and Bezos smiling and sitting in a restaurant. Phan said the photo was from 2004, meaning it may have been taken at that fateful dinner. Musk responded to the photo, tweeting, “Wow, hard to believe that was 17 years ago!” That 2013 fight over the Nasa launch pad From 2004 onwards, Musk and Bezos appeared to keep to themselves. But their rivalry continued in 2013 when things became contentious over leasing a Nasa launch pad. In 2013, SpaceX tried to get exclusive use of a Nasa launch pad. Blue Origin (along with SpaceX rival United Launch Alliance) filed a formal protest with the government to prevent SpaceX from using the pad – Bezos proposed converting it “into a commercial spaceport available to all launch companies”. Musk called the move a “phoney blocking tactic” and took another swipe at Blue Origin. “[Blue Origin] has not yet succeeded in creating a reliable suborbital spacecraft, despite spending over 10 years in development,” Musk told Space News at the time. “If they do somehow show up in the next five years with a vehicle qualified to Nasa’s human rating standards that can dock with the Space Station, which is what Pad 39A is meant to do, we will gladly accommodate their needs.” “Frankly, I think we are more likely to discover unicorns dancing in the flame duct,” he added. SpaceX eventually won the right to take over the pad. That 2014 patent battle In 2014, the two companies got into a patent battle when Blue Origin was granted a patent for drone ships, which are used for landing rocket boosters. SpaceX petitioned to invalidate the patent. Blue Origin’s ownership of the patent would mean SpaceX would need to pay to use the technology. SpaceX argued that the science in the patent was “old hat”, given that the concept of drone ships has been around for decades. A judge sided with SpaceX, leading to Blue Origin withdrawing most of the claims in the patent. How does Laurene Powell Jobs spend her US$21.7 billion fortune? Twitter spats and criticisms in interviews In recent years, Musk and Bezos have been more public about their feud, taking their rivalry to Twitter. Both execs have seized opportunities to take shots at the other, most often sniping at each other over reusable rockets. After Blue Origin successfully landed its New Shepard rocket in 2015, Bezos tweeted a video calling it “the rarest of beasts – a used rocket”. Musk responded, saying SpaceX had performed the feat three years prior. @JeffBezos Not quite "rarest". SpaceX Grasshopper rocket did 6 suborbital flights 3 years ago & is still around. pic.twitter.com/6j9ERKCNZl — Elon Musk (@elonmusk) November 24, 2015 When SpaceX landed its Falcon 9 spacecraft, Bezos took the opportunity to needle Musk on Twitter. Congrats @SpaceX on landing Falcon's suborbital booster stage. Welcome to the club! — Jeff Bezos (@JeffBezos) December 22, 2015 The feud isn’t just about space ambitions, however. Musk has taken issue with Blue Origin’s hiring practices and has taunted Bezos in interviews. Musk told his biographer, Ashlee Vance, that Blue Origin has repeatedly tried to snag talent away from SpaceX. “Blue Origin does these surgical strikes on specialised talent offering like double their salaries,” Musk said in Vance’s 2015 biography. “I think it’s unnecessary and a bit rude.” Musk also revealed that SpaceX set up an email filter for the words “blue” and “origin”, according to Space News . When the BBC asked Musk about Bezos in 2016, he responded, “Jeff who?” Musk is known for being outspoken on Twitter, and that has included jabs at Bezos. Musk has repeatedly and publicly called Bezos a “copycat” – once after Amazon announced its plan to launch internet-beaming satellites, and again when Amazon acquired self-driving-taxi company Zoox. Musk poked at Bezos in 2019 after the unveiling of Blue Origin’s concept for a lunar-landing vehicle, called Blue Moon. Oh stop teasing, Jeff 😉 pic.twitter.com/wuWPENcSE1 — Elon Musk (@elonmusk) May 10, 2019 “Putting the word ‘blue’ on a ball is questionable branding,” he tweeted. Musk later mocked up a screenshot of a New York Times article that changed the name from “Blue Moon” to “Blue Balls”. “Oh stop teasing, Jeff,” Musk wrote. For his part, Bezos has been less overt about his distaste for Musk and SpaceX, but he’s made veiled comments about his thoughts on the company’s plans. While Bezos has stopped short of calling out Musk directly, he has taken aim at Musk’s biggest ambition: colonising Mars, the main goal of SpaceX. Bezos’ focus is on getting humans to the moon, and he’s described the idea of reaching Mars as “un-motivating”. “Go live on the top of Mount Everest for a year first and see if you like it, because it’s a garden paradise compared to Mars,” Bezos said in 2019. During his presentation for Blue Moon, Bezos referenced SpaceX’s Mars ambitions once again, titling a slide about Mars “FAR, FAR AWAY”. In a wide-ranging Times interview, Musk, 49, took the opportunity to comment on Blue Origin, appearing to imply that Jeff Bezos, 56, is too old and Blue Origin too slow to ever make real progress. “The rate of progress is too slow and the amount of years he has left is not enough, but I’m still glad he’s doing what he’s doing with Blue Origin,” Musk said. Though the pair’s main point of contention appears to be space, Musk has made other pointed remarks about Amazon, recently calling the company a monopoly. After Amazon’s publishing service refused to publish a book about the coronavirus by writer Alex Berenson, Musk tweeted at Bezos that the situation was “insane” and called for Amazon to be broken up. This is insane @JeffBezos — Elon Musk (@elonmusk) June 4, 2020 Musk’s comments were in response to Amazon’s Kindle Direct Publishing service refusing to publish Berenson’s book titled Unreported Truths about Covid-19 and Lockdowns . Berenson tweeted a screenshot of an email he says he received from Amazon and said the company “censored” his book. The screenshot appeared to show the publishing division saying the book does not comply with its guidelines. Amazon later said the book was removed in error and would be reinstated. The 5 billionaires competing to be China’s richest woman Another Nasa battle – this time over a contract Last spring, Blue Origin and SpaceX were both asked to submit designs for lunar landers to Nasa for a mission to return humans to the moon by 2024. Along with a third company, Dynetics, Bezos’ and Musk’s companies were asked to compete for a multibillion-dollar contract with Nasa. All three companies had 10 months to work on their designs for a mission known as Artemis – the mission would be the first time a manned spacecraft has been sent to the moon since the Apollo 17 mission in 1972. Bezos’ unexpected praise of SpaceX It’s possible Bezos has softened his stance on SpaceX, however. After the rocket company conducted a test of its Starship spacecraft in December, Bezos publicly complimented the company for its ambitious attempt. SpaceX launched the rocket thousands of feet in the air during a seven-minute test flight, but the rocket exploded during landing. Still, the audacious test garnered praise from Musk’s space rival, Bezos. “Anybody who knows how hard this stuff is impressed by today’s Starship test,” Bezos wrote in an Instagram post, accompanied by a low-resolution photo of the rocket. “Big congrats to the whole @SpaceX team. I’m confident they’ll be back at it soon.” View this post on Instagram A post shared by Jeff Bezos (@jeffbezos) Jostling for the title of world’s richest person In January, Musk overtook Bezos to become the richest person in the world, but Bezos has since regained the top spot. Tesla hit all-time highs in the stock market in recent weeks, gradually nudging Musk’s wealth skyward – first, past Bill Gates and Mark Zuckerberg, and then, past Bezos. Bezos has since regained the lead with a net worth of US$187 billion. Musk is third, after LVMH CEO Bernard Arnault , with a fortune worth US$166 billion. Nasa’s contract with SpaceX In April, Nasa announced that SpaceX is the sole recipient of the contract for landing humans on the moon, worth US$2.9 billion. The decision infuriated Blue Origin, which is now challenging Nasa’s decision. According to The New York Times , Blue Origin filed a 50-page protest with the US Government Accountability Office, challenging Nasa’s decision as “flawed”. Nasa had initially said it would award the contract to two companies, but budget concerns and a lack of congressional funding meant it could only choose SpaceX. Blue Origin told CNBC that Nasa’s decision was unfair because it had “moved the goalposts at the last minute” and had negotiated a proposed price with SpaceX, but not with Blue Origin. Musk responded to Blue Origin’s protests with a thinly veiled jab about male anatomy. In response to The New York Times report, Musk tweeted: “Can’t get it up (to orbit) lol.” Who’s the richest Shark Tank cast member? Net worths ranked – from NBA owner Mark Cuban to Storage Now entrepreneur Kevin O’Leary Bezos’ space flight View this post on Instagram A post shared by Jeff Bezos (@jeffbezos) Bezos announced in June that he’s making a major commitment to the future of Blue Origin: he’s heading to space aboard one of his own spacecrafts. On July 20, Bezos and his younger brother, Mark, will take an 11-minute flight aboard Blue Origin’s New Shepard spacecraft. The flight will send the crew 62 miles above the Earth’s surface before returning to Earth. “Ever since I was five years old, I’ve dreamed of travelling to space,” Bezos said in a video posted on Instagram. “I want to go on this flight because it’s a thing I wanted to do all my life. It’s an adventure – it’s a big deal for me.” The short trip will be Blue Origin’s first human flight – SpaceX launched its first human passengers into orbit in May 2020. While it’s likely Musk could have gone to space himself by now, the trip would carry more risk for his business dealings, given that he’s also the CEO of a public company. Bezos, on the other hand, will step down as CEO of Amazon on July 5, two weeks before his visit to space. Want more stories like this? Sign up here. Follow STYLE on Facebook , Instagram , YouTube and Twitter . This article originally appeared on Business Insider