~ St. Maarten’s Backyard Astronomy for March 17 & 18 ~
Sun rises at 6:18am
Sun sets at 6:22pm
Moon phase: new moon, virtually absent
This weekend is stargazing central! With the moon in its new moon phase, it will be virtually absent and therefore the stars will shine all the more brightly. Get away from street lights if you can or even just by blocking a light source – you should be able to observe the stars and planets with unparalleled clarity, with or without a telescope or binoculars.
The young moon will return early next week, as a thin crescent low in the western sky after sunset, each day gaining size and altitude until, by next weekend, we will see a brilliant half circle in the noon position (directly overhead) at sunset. Another week’s time will bring us back to the full moon which rises in the east as the sun sets in the west. But for this weekend, the moon vacates the celestial stage to the stars and planets.
Mercury and Venus are the evening stars and shine in the west, briefly, setting soon after sunset. Venus is an exceedingly brilliant planet, third-brightest celestial body after the sun and moon. Mercury of course is dim and hard to spot, but from March 17 to 20, you can try this trick. Once you spot Venus at western dusk, aim your binoculars at Venus, and in the field of view with Venus will be Mercury. Mercury and Venus have been in a single binocular field all month and they still are.
Once the night is full dark and the stars twinkling down on us, Why not check out the brightest true star in the night-time sky. Sirius, in the constellation Canis Major (or Big Dog), looks extraordinarily bright because it is only 8.6 light years away from earth. That’s pretty close, as stars go.
The bright planet Jupiter is up all night now, too, and it’s brighter than Sirius. But you won’t mistake any other object for Sirius if you look at a familiar star pattern near Sirius on the sky’s dome. No matter where you live on Earth, just follow the three medium-bright stars in Orion’s Belt always point to Sirius.
By the way, many people comment that they see Sirius flashing colours whenever Sirius is low in the sky. The colours are just the ordinary rainbow colours in white starlight; all starlight is composed of this mixture of colours. We notice the colours of Sirius more readily, though, because Sirius is so much brighter than most stars! So the colours are intrinsic to Sirius, as they are to all stars, but it’s Earth’s atmosphere that causes us to notice them. When you see Sirius low in the sky, you’re looking through a greater thickness of atmosphere than when the star is overhead. The atmosphere splits the starlight into its colours like how a prism does, as the time lapse photo shows.
This coming Tuesday, March 20, is the Spring Equinox. That is the day when the tilt of the earth’s axis aligns with the sun’s path across our sky. In other words, the sun’s rays will be shining directly onto the earth’s equator. This results in the hours of daylight being equal to the hours of darkness. This day is often called the First Day of Spring or the Vernal Equinox. Whatever you call it, it’s a great time to appreciate nature, and consider the balance of yen and yang in our lives.
Thank you for keeping up with the Night Sky articles. If you are out later on in the week, each star rises about four minutes earlier each day than written here, and the moon rises 50 minutes later. Night Sky is researched and compiled by Lisa Davis-Burnett. Earthsky.org is a key resource for information and images. Questions or comments? Email This email address is being protected from spambots. You need JavaScript enabled to view it.
