You are here

Eclipses, Occultations and Transits

An eclipse is the result of the total or partial masking of a celestial body by another along an observer’s line of sight. Solar eclipses result from the Moon blocking the Sun relative to the Earth; thus Earth, Moon and Sun all lie on a line. Lunar eclipses work the same way in a different order: Moon, Earth and Sun all on a line. In this case the Earth’s shadow hides the Moon from view. An occultation occurs when a celestial object is eclipsed by the Moon or another solar system body. A transit is either the act of one celestial body passing in front of another or the time at which a celestial object is highest in the sky. The time at which a celestial object crosses the meridian is called the transit time.

Radio Programs

Bright Pairs Bright pairings in the dawn sky December 2, 2017

Moon and Regulus A big star disappears from view October 14, 2017

Eclipse Site? A plethora of solar eclipses September 2, 2017

Eclipse Day Two chances to see an eclipse August 21, 2017

Ready for the Eclipse Getting ready for the big event August 20, 2017

Eclipse Predictions Predicting a skywatching spectacle August 19, 2017

Eclipse Watching Safety tips for a skywatching spectacle August 18, 2017

More Eclipse Science Chasing a shadow from the sky August 17, 2017

Eclipse Science Studying a solar mystery August 16, 2017

Moon on the Move The Moon moves across the sky August 15, 2017

Solar Eclipse A journey from day to night August 14, 2017

Moon and Venus Beautiful encounters with the Moon June 19, 2017

Moon and Regulus Repeat appearances for a bright star May 30, 2017

Northern Crown Crowning the northern sky May 27, 2017

Moon and Aldebaran The Moon plays a game with a star March 4, 2017

Annular Eclipse Covering up most of the Sun February 26, 2017

Faint Eclipse A disappointing lunar eclipse February 9, 2017

Big Year A big year ahead in the sky January 1, 2017

Moon and Aldebaran Disappearing in the moonlight December 12, 2016

Algol A stellar ghoul for Halloween October 31, 2016

Moon and Aldebaran Four years of hide-and-seek October 18, 2016

Annular Eclipse A ring of fire around the Moon August 31, 2016

Vanishing Act Covering up the eye of the bull July 28, 2016

Bright and Close Cutting off the light of a star July 9, 2016

Mercury Transit II The clockwork precision of a planet May 8, 2016

Crossings The Moon, Mercury, and two stars May 7, 2016

Mercury Transit Dotting the face of the Sun May 6, 2016

Moon and Aldebaran Years of playing “peek-a-boo” January 19, 2016

Blood Harvest Super Moon Lining up names for the full Moon September 26, 2015

Lunar Eclipse Lining up a skywatching treat September 25, 2015

Moon and Aldebaran A stellar disappearing act September 3, 2015

Moon and Spica Creeping up on a bright star April 30, 2015

Lunar Eclipse Lining up a total lunar eclipse April 2, 2015

Eclipses Through the Ages A legacy from 1492 April 1, 2015

Solar Eclipse Extra darkness for the Arctic March 18, 2015

Occultations Illumination from darkness January 22, 2015

Moon and Uranus The Moon takes aim at a faint giant November 30, 2014

Epsilon Aurigae Playing Frisbee with a bright star November 22, 2014

Solar Eclipse Darkening the afternoon sky October 21, 2014

Lunar Eclipse A repeat performance for the Moon October 6, 2014

Dabih Covering up a passel of stars September 4, 2014

More Lunar Eclipse Big entertainment in the night sky April 13, 2014

Lunar Eclipse Changing the course of history April 12, 2014

Moon and Spica Lining up a lunar encounter January 21, 2014

Solar Eclipse A rare solar eclipse November 1, 2013

Hunter’s Moon Hunting up a faint eclipse October 17, 2013

Moon and Spica Lining up a celestial encounter July 14, 2013

A New Cycle Beginning a new lunar cycle May 23, 2013

Annular Eclipse A ring of fire above the Pacific Ocean May 8, 2013

Moon and Spica Illumination from a disappearing act February 27, 2013

Epsilon Geminorum A star by the numbers January 16, 2013

Feeble Eclipse Earth casts a feeble shadow on the Moon November 26, 2012

Solar Eclipse Diving into a natural wonder November 11, 2012

Eclipse Watcher Risking life and limb for a solar eclipse August 18, 2012

Cloudy Skies A cruel twist of nature August 17, 2012

Solar Spotters Getting a better bead on the Sun June 5, 2012

Venus Transit II A last-in-a-lifetime event June 4, 2012

Venus Transit Measuring out a solar-system ruler June 3, 2012

Partial Lunar Eclipse Taking a “bite” out of the Moon June 2, 2012

Celestial Geometry A hubbub over celestial geometry June 1, 2012

Transit and Eclipse Lining up with Earth and the Sun May 31, 2012

Annular Eclipse II Cycling through centuries of eclipses May 19, 2012

Annular Eclipse A ring of fire in the afternoon sky May 18, 2012

Happy Coincidence A beautiful scientific coincidence May 17, 2012

Clockwork Eclipses Ticking off the hours until a solar eclipse May 16, 2012

Balloon Ride Taking a balloon ride for science April 6, 2012

Rings of Uranus A dark discovery for a giant planet March 7, 2012

Featured Images

Baily's Beads around the Moon

Brilliant Beads August 21, 2017

Solar eclipse sequence

Anatomy of an Eclipse August 20, 2017

Proper eye protection is needed for safe eclipse viewing

Safety First! August 18, 2017

The Sun sets behind a NASA WB-57F Canberra research aircraft

Chasing a Shadow August 17, 2017

The Sun's corona shines around the intervening Moon during a total solar eclipse

Solar Mystery August 16, 2017

Map showing the circumstances of the August 21, 2017, total solar eclipse

The Right Path August 14, 2017

Annular solar eclipse

Fiery Ring August 31, 2016

Moon-Aldebaran occultation

Vanishing Act July 28, 2016

Mercury transits the Sun, May 2016

Little Black Dot May 10, 2016

2006 transit of Mercury

Spotty Sun May 6, 2016

Total lunar eclipse, October 2014

Lunar Eclipse September 26, 2015

Space-based view of solar eclipse of March 20, 2015

Disappearing Sun March 20, 2015

Artist's concept of Epsilon Aurigae

Playing Frisbee November 23, 2014

The Moon occults Dabih, a star in Capricornus

Celestial Cover-Up September 5, 2014

Peek-a-Boo January 31, 2014

Solar eclipse of August 19, 1887, from near Berlin

Fire in the Sky August 18, 2012

June 5, 2012, Venus transit from International Space Station

Seeing Spots June 9, 2012

Diagram of Venus transit of June 5, 2012

Sun Spot June 4, 2012

Partial lunar eclipse of June 4, 2012

Lunar Nibble June 2, 2012

Illustration of annular eclipse of May 20, 2012

In the Zone May 18, 2012

Venus's path across the Sun during the transit of 1761

Bright Passage June 6, 2011

Total Lunar Eclipse of December 21, 2010

Disappearing Moon December 20, 2010