Mali Coconut

Earth and the Moon are in a constant dance as they orbit the Sun — and in June 2020, they’ll create two special celestial events. 

June 20: Summer solstice in the Northern Hemisphere 

Earth has a slight tilt as it orbits the Sun, and June is one of two times each year when that tilt is most prominent: a solstice. At the solstices, which happen each year in June and December, Earth’s tilt is at the greatest angle with respect to the plane of its orbit, meaning that one hemisphere is tilted towards the Sun, and the other hemisphere is tilted away. 

In the Northern Hemisphere, June 20 is the summer solstice — the Northern Hemisphere is tilted towards the Sun, so the June solstice is the day on which the Northern Hemisphere receives the longest stretch of daylight for the year.

In both hemispheres, the Sun will rise and set at its northernmost point on the horizon. After June 20, the Sun will appear to travel south.

This view from our Earth Polychromatic Imaging Camera on the National Oceanic and Atmospheric Administration's DSCOVR satellite shows the change in Earth’s tilt between the June and December solstices.

During the June solstice, the Southern Hemisphere is tilted away from the Sun, meaning the June solstice marks its shortest stretch of daylight for the year. June is the Southern Hemisphere’s winter solstice.  

June 21: Annular solar eclipse in Africa and Asia

The day after the solstice will see another special celestial event: an annular eclipse. Eclipses happen when the Moon lines up just right between the Sun and Earth, allowing it to block out part or all of the Sun’s bright face and cast a shadow on Earth. Though the Moon orbits Earth about once a month, its orbit is tilted by five degrees, so the perfect alignment that creates an eclipse is relatively rare. Often the Moon is too high or low in our sky to block out the Sun.

The June 21, 2020, eclipse is an annular eclipse visible primarily in Africa and Asia. During an annular eclipse, the Moon is too far from Earth and its apparent size is too small to entirely block out the face of the Sun, leaving a sliver of the Sun visible around the Moon’s edge during the eclipse and creating a “ring of fire” effect.

Credit: Dale Cruikshank

Outside the path of annularity, people in other parts of Africa, Asia and even some of Europe and the Pacific have a chance to see a partial solar eclipse, weather permitting. The degree of the partial eclipse depends on how close you are to the path of annularity. Locations far from the path of annularity will see only a small part of the Sun covered by the Moon, while places close to the path will see almost all of the Sun obscured.

No matter where you are, you must take safety precautions to watch the eclipse safely. There is no part of an annular eclipse during which it is safe to look directly at the Sun. You must use a proper solar filter or an indirect viewing method during all phases of the eclipse — even if only a tiny sliver of the Sun is visible around the Moon’s edge, that’s still enough to cause damage to your eyes.