Total Solar Eclipse

February 12, 2017 in Education by Scott Logan

Total Solar Eclipse

Credit: The May 20, 2012, solar eclipse, as seen from Japan. Hiroki ONO/Flickr

It’s a good bet that most of us will not be in Indonesia for the Total Solar Eclipse next week. For those of you that are, the rest of us are envious.

Solar eclipses occur when the Moon strays in between Earth and the Sun, temporarily blocking out the sunlight. There are generally at least two solar eclipses around the world every year, but while that might make them sound relatively common, the chances of being in the right place at the right time is fairly slim. For example, the last total solar eclipse visible from the United States was in 1979, with the next one 2024.

As beautiful as the solar eclipse may be, staring at the Sun (even when it’s partially blocked out) for even a few seconds can harm your eyes due to the intense UV radiation. As such, you must use special equipment to view them. You can either purchase a pair of solar eclipse glasses, or make your own equipment as this NASA guide shows.

March Equinox

February 12, 2017 in Education by Scott Logan

March Equinox – Equal Day and Night, Nearly

There are two equinoxes every year – in March and September – when the Sun shines directly on the equator and the length of night and day are nearly equal.

March equinox illustration

The Earth during the equinox. (Not to scale)

March Equinox in San Antonio, Texas, U.S.A. is on
Saturday, March 19, 2016 at 11:30 PM CDT (Change city)

March Equinox in Universal Coordinated Time is on
Sunday, March 20, 2016 at 04:30 UTC

The Sun Crosses the Equator

The March equinox marks the moment the Sun crosses the celestial equator – the imaginary line in the sky above the Earth’s equator – from south to north. This happens on March 19, 20 or 21 every year.

10 Facts About the March Equinox

Northern Spring – Southern Fall

Equinox and solstice illustration
Equinox and solstice.

Equinoxes and solstices are opposite on either side of the equator, and the March equinox is also known as the “spring (vernal) equinox” in the Northern Hemisphere and as the “autumnal (fall) equinox” in the Southern Hemisphere.

Why is it Called “Equinox”?

On the equinox, night and day are nearly exactly the same length – 12 hours – all over the world. This is the reason it’s called an “equinox”, derived from Latin, meaning “equal night”. However, in reality equinoxes don’t have exactly 12 hours of daylight

What Happens on the Equinox?

The Earth’s axis is always tilted at an angle of about 23.4° in relation to the ecliptic, the imaginary plane created by the Earth’s path around the Sun. On any other day of the year, either the Southern Hemisphere or the Northern Hemisphere tilts a litte towards the Sun. But on the two equinoxes, the tilt of the Earth’s axis is perpendicular to the Sun’s rays, like the illustration shows.

Celebrating new Beginnings

The March equinox has long been celebrated as a time of rebirth in the Northern Hemisphere. Many cultures celebrate spring festivals and holidays around the March equinox, like Easter and Passover.

The Snake of Sunlight

Illustration image
“The snake of sunlight” at Chichen Itza, Mexico.

One of the most famous ancient Spring equinox celebrations was the Mayan sacrificial ritual by the main pyramid at Chichen Itza, Mexico.

The main pyramid – also known as El Castillo – has four staircases running from the top to the bottom of the pyramid’s faces, notorious for the bloody human sacrifices that used to take place here.

The staircases are built at a carefully calculated angle which makes it look like an enormous snake of sunlight slithers down the stairs on the day of the equinox.

The Mayan Calendar was very precise in this respect, but today the Mayan calendar is most famous for ending exactly at 11:11 UTC on the 2012 December Solstice.

Knowledge of the equinoxes and solstices is also crucial in developing dependable calendars, another thing the Mayans clearly had got the hang of.