a guide to the sky
Android app helps users build analemmatic sundial
By MARCELO DE OLIVEIRA SOUZA
Sky ’ s Up Editor
In a very distant past people noticed that there was a variation in the size and direction of an object ’ s shadow during the day . Following and analyzing these variations it was possible to build the first instrument to determine the hours during the day : The Sundial . The main idea of sundials is to associate the variation of the shadow of an object , which is called a Gnome , with the hours of the day . Today there are a large number of sundial models . One model stands out because it uses people like the Gnomon . This sundial with human interaction is called the Analemmatic Sundial . This model of sundial has an ellipse-shaped hour scale and in the center of the ellipse another vertical scale with the months of the year . In the Analemmatic Sundial , the Gnomon ( the object that will cast its shadow to mark the time ) is anyone who will position himself on the scale that is in the center of the ellipse . It is an excellent sundial to build in public places . I , Marlon Pessanha and Jorge André Ferreira Machado developed
here . The Analemmatic Sundial is an excellent educational tool to talk about the tilt of the Earth ’ s axis , the annual movement of the Earth around the Sun and the apparent movement of the Sun .
( All times in Universal Time – UT ) April – Global Astronomy Month 6 — Conjunction of the Moon and Saturn 7 — Conjunction of the Moon and Jupiter 10 — Mercury at greatest western elongation at 17:00h 12 — New Moon at 3:30h a . m . 16-18 — 13th International Meeting of Astronomy and Astronautics – doity . com . br / 13imaa 17 — Conjunction of the Moon and Mars 17 — Lunar occultation of Mars ( visible only in part of Asia ) 18 — Mercury in superior conjunction 20 — Moon First Quarter at 7:58h a . m . 21-22 — Peak of the Lyrid Meteor Shower 27 — Full Moon at 4:31h a . m . with the Moon at perigee
May 3 — Moon Last Quarter at 8:50h p . m . 3 — Conjunction of the Moon and Saturn 4 — Conjunction of the Moon and Jupiter 4-5 — Peak of the Eta Aquarid Meteor Shower 11 — New Moon at 7:59h p . m .
12 — Conjunction of the Moon and Venus 13 — Conjunction of the Moon and
Mercury 17 — Mercury at greatest elongation east 19 — Moon First Quarter at 8:12h p . m . 26 — Full Moon at 12:13h p . m . 26 — Total Lunar Eclipse - visible Australia , parts of the western US , western South America , or in South-East Asia . Greatest eclipse at 11:18h . 29 — Conjunction of Venus and Mercury 30 — Conjunction of the Moon and Saturn
June 1 — Conjunction of the Moon and Jupiter 2 — Moon Last Quarter at 8:24h a . m . 10 — New Moon at 11:52h a . m . 10 — Annular Solar Eclipse - visible from parts of Russia , Greenland , and northern Canada . Greatest eclipse at 10:41h . 10 — Mercury in inferior conjunction 12 — Conjunction of the Moon and
Venus 13 — Conjunction of the Moon and Mars 18 — Moon First Quarter at 4:54h a . m . 21 — June Solstice at 3:32h a . m . 24 — Full Moon at 7:39h a . m . 27 — Conjunction of the Moon and Saturn 28 — Conjunction of the Moon and Jupiter
July 1 — Moon Last Quarter at 10:10h p . m . 8 — Conjunction of the Moon and Mercury 10 — New Moon at 2:16h a . m . 12 — Conjunction of the Moon and Venus 13 — Conjunction of Venus and Mars 17 — Moon First Quarter at 11:10h a . m . 24 — Full Moon at 3:36h a . m . 24 — Conjunction of the Moon and Saturn 25 — Conjunction of the Moon and Jupiter 28-29 — Peak of the Delta Aquarid Meteor Shower 31 — Moon Last Quarter at 2:15h p . m .
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