Calendar

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Mother’s Day (USA)

Mother's Day in the United States is an annual holiday celebrated on the second Sunday in May. Mother's Day recognizes mothers, motherhood and maternal bonds in general, as well as the […]

Sir John Herschel FRS died 1871

Sir John Frederick William Herschel, 1st Baronet KH FRS (/ˈhɜːrʃəl, ˈhɛər-/; 7 March 1792 – 11 May 1871) was an English polymath, mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint, and did botanical work. Herschel originated the use of the Julian day system in astronomy. He […]

New Moon

New Moon. By the modern definition, New Moon occurs when the Moon and Sun are at the same geocentric ecliptic longitude. The part of the Moon facing us is completely […]

Moon at Apogee

The Moon’s distance from Earth varies throughout its monthly orbit because the Moon’s orbit isn’t perfectly circular. Every month, the Moon’s eccentric orbit carries it to apogee – its most distant point from […]

Eid al-Fitr begins at sundown (Muslim)

Eid al-Fitr (/iːd əl ˈfɪtər/ eed əl FIT-ər; Arabic: عيد الفطر‎ ʻĪd al-Fiṭr, IPA: ), also called the "Festival of Breaking the Fast" or Lesser Eid, is a religious holiday celebrated by Muslims worldwide that marks the end of the month-long dawn-to-sunset fasting of Ramadan. This […]

Astronomy Day

Astronomy Day is an international event observed each fall and spring near the first quarter Moon. Local astronomical societies, planetariums, museums, and observatories sponsor public viewing sessions, presentations, workshops, and other activities to increase public awareness about astronomy and our wonderful universe.

This fall, Astronomy Day will be held on October 12, 2021.

Conjunction of Mars & Moon

The planet Mars will appear in conjunction with the Moon in the western sky after sunset on this May 15, 2021.

Recurring

Astronomy Day

Astronomy Day is an international event observed each fall and spring near the first quarter Moon. Local astronomical societies, planetariums, museums, and observatories sponsor public viewing sessions, presentations, workshops, and […]

International Day of Light

The International Day of Light is a global initiative that provides an annual focal point for the continued appreciation of light and the role it plays in science, culture and […]

St. Brendan, patron of navigators who steer by celestial bodies

Brendan of Clonfert (c. AD 484 – c. 577) Brénainn moccu Alti or Brénainn maccu Alti (Irish: Naomh Bréanainn or Naomh Breandán; Latin: Brendanus; Icelandic: (heilagur) Brandanus), also referred to as "Brendán moccu Altae" (Brendan of the Fosterling Folk), called "the Navigator", […]

World Telecommunication and Information Society Day

Theme: "Accelerating Digital Transformation in challenging times​"​. ​​ World Telecommunication and Information Society Day ​(WTISD) has been celebrated annually every 17 May since 1969 to mark the founding of ITU […]

First Quarter Moon

The Moon is at First Quarter on May 19th - it is visible high in the southern sky in early evening.

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World Metrology Day.

World Metrology Day is an annual celebration of the signature of the Metre Convention on 20 May 1875 by representatives of seventeen nations. The Convention set the framework for global […]

Official Calendar

2023 Vatican Observatory calendars now available for purchase in our e-store!