Edward Snowden, the former National Security Agency contractor whose leaked documents opened a worldwide discussion about government surveillance, joined Twitter this morning. So far, he's amassed more than 400,000 followers, but he follows only one account: @NSAGov.

Can you hear me now? — Edward Snowden (@Snowden) September 29, 2015

Twitter created a GIF showing how his account acquired followers around the world in just a few hours.

The @Snowden account carries a blue check mark, indicating that his identity has been verified by Twitter. His only substantive conversation so far has been with Neil deGrasse Tyson, the astrophysicist and all-around science-communicator-guy, who recently interviewed Snowden on his show Star Talk Radio.

Ed @Snowden, If you visit Mars, I'd bet any life forms there will greet you with a sip of that water -- and a tourist visa. — Neil deGrasse Tyson (@neiltyson) September 29, 2015

Snowden has been living in Russia since he shared NSA documents with journalists in 2013. Today, he said he's keeping busy working on "secret projects" for the Freedom of the Press Foundation, "but I still find time for cat pictures."

"Many call you Hero, others Traitor... What do you say to those labels?" Tyson asked.

"Hero, traitor—I'm just a citizen with a voice," he responded. "Daniel Ellsberg told me labels never stopped progress. Neither in 1776 nor today."