Which sentence is punctuated correctly?

Scientists know that Earth has been impacted by large asteroids in the past; however, what happens if a major asteroid hits Earth now?

Scientists know that Earth has been impacted by large asteroids in the past however; what happens if a major asteroid hits Earth now?

Scientists know that Earth has been impacted by large asteroids in the past, however what happens if a major asteroid hits Earth now?

Scientists know that Earth has been impacted by large asteroids in the past however what happens if a major asteroid hits Earth now?

1 answer

The correct sentence is: "Scientists know that Earth has been impacted by large asteroids in the past; however, what happens if a major asteroid hits Earth now?"