• Elon Musk and Jeff Bezos, the two richest people in the world, have been rivals for 15 years. 
• Musk has called Bezos a copycat and made digs about his rocket company, Blue Origin.
• Now, Bezos is heading to space himself aboard Blue Origin’s New Shepard spacecraft.
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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.