Earth's present-day climate change is human-induced, but the gravitational tugs of other planets can also cause long-term climatic patterns by slightly changing our planet's orbit. Now, research suggests that massive passing stars can alter Earth's path, too — and that these cosmic tugs may limit researchers' ability to study the links between past changes in Earth's orbit and our planet's climate.
Aspects of Earth's path around the sun change over time. For instance, the shape of Earth's orbit shifts between being nearly circular and elliptical every 100,000 years or so, as Jupiter and Saturn pull on Earth. This Milankovitch cycle affects how much solar radiation our planet receives, partially altering our climate and periodically sending us into ice ages.
