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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

Moon and Aldebaran Covering up a bright star July 9, 2018

Venus and Regulus Venus and the heart of the lion July 7, 2018

Solar Eclipse A mediocre year for solar eclipses February 14, 2018

Eclipsed Blue Moon A super blue lunar eclipse January 30, 2018

Moon and Aldebaran Moving the Moon across the sky January 26, 2018

Beta Ceti The imprint of a magnetic “fossil” January 12, 2018

Moon and Regulus Hiding behind the Moon January 4, 2018

Moon and Aldebaran Calibrating the dark Moon December 30, 2017

Ringed Dwarf Rings around a distant iceball December 22, 2017

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

Featured Images

Total lunar eclipse, 2014

Super Blue Lunar Eclipse January 30, 2018

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