Equinoxes & Solstices · September 23, 2027
A seasonal turning point. See the exact time where you are.
Begins
When it happens
Global reference time: September 23, 2027 at 06:01 UTC. Your local calendar date may differ.
This marks a seasonal boundary, rather than a brief visible sky event.
What to expect
A seasonal milestone that occurs at one global instant, with opposite seasons in the two hemispheres.
Understand the moment
Earth’s rotation axis is tilted about 23.4 degrees from the perpendicular to its orbital plane. As Earth travels around the Sun, that tilt changes sunlight angle and day length in each hemisphere, producing opposite seasons in the north and south.
Try it in the astronomy lab
Follow Earth around the Sun and compare its position six months apart. Its changing distance from the Sun is not the main cause of our seasons.
Opens . Each scene is an exact daily sample, without interpolation; it is separate from the catalog peak of 06:01 UTC.
How to read the scene: This orbital lesson does not calculate local day length or use the globe’s illustrative surface orientation to reproduce an equinox or solstice. The event time above is the exact catalog milestone.
A little context. A better view.
Equinoxes and solstices are calculated from the Earth–Sun geometry. Their exact times are global; the local calendar date can differ by time zone.
A June solstice marks the start of astronomical summer in the Northern Hemisphere and winter in the Southern Hemisphere. Event details identify both hemispheres.
An equinox or solstice is not a brief object appearing in the sky. No special equipment or clear weather is required to mark the instant in your calendar.
Astronomical season boundaries do not predict a particular temperature or a sudden weather change. Local climate and seasonal weather follow their own patterns.
Learn more: U.S. Naval Observatory astronomical data
Astronomical autumn begins in the Northern Hemisphere and spring in the Southern Hemisphere.
Astronomical winter begins in the Northern Hemisphere and summer in the Southern Hemisphere.
Astronomical spring begins in the Northern Hemisphere and autumn in the Southern Hemisphere.
Astronomical summer begins in the Northern Hemisphere and winter in the Southern Hemisphere.
Take the sky with you
Open the astronomy calendar in Forecast Bar to explore events alongside your local weather and astronomy alert settings.
