7 July

1816: On 7 July 1816, Rudolf Wolf was born.

Wolf was a Swiss astronomer and astronomical historian. Wolf's main contribution was the discovery of the eleven-year sunspot cycle. He was also the co-discoverer of its connection with geomagnetic activity on Earth.

In 1849 he devised a system now known as Wolf's sunspot numbers. This system is still in use for studying solar activity by counting sunspots and sunspot groups.

1668: On 7 July 1668, Isaac Newton received his Master's degree from Trinity College at the University of Cambridge, UK.