Earth is bracing for blackouts after the sun unleashed a massive X-class solar flare — the most powerful it can generate — Tuesday evening.

Thursday’s flare was much smaller, reaching only X9 strength. It was, however, the strongest this year, beating out an X7.1 flare that erupted earlier this week and an X8.7 flare in May ( which Earth dodged ). The latter was considered the strongest since 2005 — a feat seemingly bested by Thursday’s activity.