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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

One Month to Go One month and counting September 14, 2023

Eclipse Flights Soaring high to meet an eclipse September 10, 2023

Moon and Antares The Moon hides the heart of the scorpion August 24, 2023

New Moon Lining up the new Moon July 17, 2023

Solar Eclipse Solar eclipses now and later April 19, 2023

Moon and Jupiter A double disappearing act for Jupiter March 21, 2023

Moon and Mars Brilliant Mars disappears December 7, 2022

Algol The perfect star for Halloween October 30, 2022

Solar Eclipse The act of a predictable family October 24, 2022

Capricornus The weird and wonderful sea-goat October 9, 2022

Confirming Einstein A long journey into darkness September 21, 2022

Missing Handle A teapot loses part of its handle September 5, 2022

Moon and Planets The Moon takes aim at a planet June 23, 2022

Lunar Eclipse II Walking through a shadow May 15, 2022

Lunar Eclipse Months, semesters, and years for the Moon May 13, 2022

Solar Eclipse Murky skies for South America April 29, 2022

Lunar Eclipse The Moon steps into a shadow November 18, 2021

Rounding Off Earth Rounding off planet Earth November 17, 2021

Annular Eclipse A “ring of fire” across the top of the world June 9, 2021

Moon and Saturn Changing the lighting on the Moon May 29, 2021

Lunar Eclipse A brief total eclipse of the Moon May 25, 2021

Solar Eclipse Lining up an impressive light show December 13, 2020

Moon and Venus Crossing paths in the afternoon sky December 11, 2020

Penumbral Eclipse Cycling through some lunar eclipses November 29, 2020

VV Cephei A big, messy star system October 3, 2020

More Moon and Mars Mars and the Moon snuggle close September 5, 2020

Father Hell Taking the measure of the solar system May 15, 2020

Variable Stars Some un-constant stars February 20, 2020

Moon and Mars Stage magic in the pre-dawn sky February 17, 2020

Penumbral Eclipse A barely there lunar eclipse January 10, 2020

Annular Eclipse A ring of fire in eastern skies December 25, 2019

Transits Peeking in on other planets November 11, 2019

Morning Treats Skywatching treats in the morning sky November 10, 2019

Mercury Transit Crossing the face of the Sun November 8, 2019

Moon and Saturn Lining up the Moon and planets August 11, 2019

Solar Eclipse A repeating celestial lineup July 2, 2019

Lunar Eclipse II A repeat performance for the Moon January 20, 2019

Lunar Eclipse Snuggling close to the Moon January 18, 2019

Moon and Aldebaran A last rendezvous September 1, 2018

Solar Discovery Discovering a key part of the Sun August 17, 2018

Solar Eclipse Calculating a shadowy alignment August 10, 2018

Lunar Eclipse Passing through a wide shadow July 26, 2018

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

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

Featured Images

Scientists prepare to film a 1922 solar eclipse to test Einstein's theory of gravity

Ready to Roll September 21, 2022

Falling Skies January 20, 2022

Eclipsed Moon

Darkening the Moon November 18, 2021

annular solar eclipse

Ring of Fire June 9, 2021

2006 Mercury transit

Seeing Spots November 8, 2019

Total solar eclipse of August 21, 2017

Disappearing Sun July 1, 2019

Collage of images related to solar eclipse of May 1919, which made Albert Einstein world famous

Getting Famous May 29, 2019

Total lunar eclipse

Lunar Eclipse January 20, 2019

Sketches of the total solar eclipse of August 1868

Solar Discovery August 17, 2018

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