The planet’s rotation fluctuates as it travels around the sun, and measurements suggest we’re losing more than a millisecond during the long days of summer.

When the moon is positioned farther from Earth's equator and closer to the poles, its pull on the planet becomes weaker. With less resistance, Earth is able to spin a bit faster, which makes the day slightly shorter than usual.

July 9 will be one of the shortest days ever, as Earth is spinning faster and scientists are still working to understand why. According to the International Earth Rotation and Reference Systems Service (IERS) the organization that continuously measures Earth's orientation in space and the length of days,