All about eclipses

Watch the solar dance in the mornings this month

Hi Sky Guys and Gals

It’s your sky guy back for another month.

We have just had a solar eclipse down in the U.S. and will actually have one here on P.E.I. in 2024. Some people believe that solar eclipses are rare, but in actuality, there can be three to four per year. However, 70 per cent of the Earth’s surface is water, and thus 70 per cent of solar eclipses will be over water. Solar eclipses are also narrow in the area they cover and may at times, only touch down for a short time. Thus a solar eclipse will be quite rare at any given point. Let’s step back and look at what a solar eclipse actually is. We had previously described a lunar eclipse where the Earth passes between the moon and the sun and casts its shadow on the moon. In a solar eclipse, the moon passes between the Earth and the sun, and the moon’s shadow is cast upon our Earth. But, the solar eclipse is a much smaller shadow on the Earth because: a) the moon is small, and b) it is at a distance, which casts a small shadow. When the moon is between the Earth and the sun, but a little above or below, we can’t see it and we call it a new moon. To have an eclipse, it has to be directly in between.

However, it’s even more complicated. The moon is not always at the same distance from the Earth. It can be a far enough distance from us that it will not totally cover the moon. There will be a ring of sunlight left around the moon. We call this an annular eclipse of the sun. Many things happen as the totality nears. It darkens of course, it rapidly cools, waves of light are seen racing across the ground, birds stop chirping, and we humans stand in awe.

Solar eclipses are beautiful but can be dangerous. We must never – eclipse or not – look at the sun directly. We need to use Mylar glasses, or #14 welder’s glass. We can also look at the sun indirectly by projecting it on a screen.

While a lunar eclipse lasts for hours, the totality of a solar eclipse can last as little as two minutes or no longer than 7.5 minutes – not much time to see it unless you are ready.

Well, what’s in the sky for us this month?

It’s actually very exciting in the morning sky this month so I’ll describe the morning first and then the rest of our month.

First, the dance of the planets and yes, also the moon. This is a morning event and we should watch as early as Sept. 7 and thence through until Sept. 24. Venus, Regulus (the star), Mars, and Mercury all line up from top right to bottom left, and on Sept. 17, the moon joins the line. Why dance? Because in the line, Mars, Mercury, Regulus, the moon, and even Venus change places with each other, but most especially Mars and Mercury.

On Sept. 7, top left is Venus, then Mercury, Regulus, and Mars rather clumped together. If you can, get up and follow them before dawn from morning to morning. A real treat. Note that around Sept. 24, Mercury will sink back into the dawn sky.

Now the evening. It’s nothing like the morning but it still holds its own. Jupiter and Saturn are still there. Jupiter – its days are now numbered for this apparition. It is low in the west southwest all month. In early September it sets about two hours after the sun and this is down to less than one hour by month’s end. The Galilean moons will remain visible. By late in the month, very little detail of Jupiter can be seen in a telescope.

Saturn is much better. It’s about 30 degrees above the southern horizon at sunset, and as the sky darkens, you should see Antares 13 degrees west southwest. The pair sets about 12:30 a.m. at month’s beginning, and about half an hour earlier each week.

Dates to watch

The Autumnal Equinox is Sept. 22 at 5:02 p.m. This is the date when autumn begins. Full moon on Sept. 6 New moon on Sept. 20