Complex sentence: Roughly every one thousand years, a red giant in a highly eccentric orbit approaches Ishtar closely enough to cause a rise in temperatures and subsequently, severe weather changes such as droughts and storms for over a century.
Split into simpler sentences: Roughly every one thousand years, a red giant in a highly eccentric orbit approaches Ishtar closely enough to cause a rise in temperatures. Subsequently, severe weather changes such as droughts and storms occur for over a century.