Every couple of years, Earth passes near to Mars. But because Mars’ orbit is quite elongated (“elliptical”), the distance between the two planets can get much closer every 15-17 years. This year was one of these closest approach years, with Mars just 62 million km away on October 6^th. Ok, not close enough to ever worry about ever hitting Mars; but if you are in the business of sending spacecraft to other world, this is the best time to do so. And indeed, the US, China and the United Arab Emirates each launched their own mission to Mars this year, all expected to arrive there in February next year.  

Both planets, of course, are continuing to travel along their respective orbits about the Sun. As the Earth moves faster along its smaller inner orbit closer to the Sun, it overtakes Mars travelling in its more distant orbit, like race cars travelling along an oval racetrack. From our perspective here on Earth, as Earth overtakes Mars, Mars will be seen in the opposite direction from the Sun. Hence, we use the term “opposition” to describe these events. And if Mars is currently opposite the Sun, that means it rises in the East at sunset and will spend the whole night crossing the sky to set in the West at sunrise!   Mars continues to appear to the unaided eye as an unusually bright, orangey coloured “star” in the Eastern sky after sunset until the end of October. It will then begin to fade noticeably as the distance between the two planets steadily increases. Although it will rise earlier each night and stays high in the sky through the night, it will have dropped five-fold in brightness by Christmas time. So enjoy Mars now while it’s at its best! If you have a telescope, even a small telescope, this is your best opportunity to see Mars through your scope for the next 15 years!!! Here’s a sample of what our members have been able to achieve in 2020… 

-DDO Defenders 😁

The Orionids meteor shower peaks on the night of Tuesday October 20-21. This is a modest shower, producing about 20 meteors (“shooting stars”) per hour if you are viewing away from city light pollution. Of course, the sky needs to be clear. And expect to see less than half that number if you are observing from a moderately dark backyard in the suburbs. The crescent moon sets at around 9:30 pm on this night and so won’t spoil the view this year.  

It takes at least 15 minutes for your eyes to fully adjust to the dark so you can see the fainter meteors (…there are many more fainter meteors than bright ones). Turn off all yard lights and find a place that is shielded from seeing your neighbour’s lights or streetlights. Even looking at your phone’s display can cause you to lose your dark adaption and you will need another 15+ minutes in the dark to restore it. 

You will need to wait till about 10:30 pm EDT before any of these meteors will become visible. That is when the “radiant” for this shower rises above the Eastern horizon. If the sky is clear and you do indeed start your viewing right at 10:30 (till ~11:00 pm), you have a chance to catch an impressive “earth-skimmer” meteor, one that remains visible for a longer time as it streaks across a much longer path across the sky. 

To watch the Orionids or any other meteor shower, I strongly recommend you find yourself a fully reclining full length deck chair (Chaise Lounge) so you can be off of the ground and comfortably looking straight overhead without having to bend your neck. That is where you want to be looking, straight overhead to see the most meteors. The meteors will seem to be coming from a particular point in the sky, the shower’s “radiant”: whichever constellation the radiant lies in is how a meteor shower gets its name. In this case, the radiant lies in the constellation of Orion. But each meteor can be almost anywhere in the sky when it first lights up; and then it usually travels less than a quarter of the distance from horizon to horizon before it stops glowing.  

For those interested in knowing what an Orionid meteor is made of, you might be surprised to learn they are pieces of Comet Halley, which last passed by the Earth in 1986. Comets leave behind a trail of rock dust that fills the path they take as they orbit the Sun. Earth passes through that thin debris trail twice each year, producing the Orionid meteor shower in the Fall and the Eta Aquarids meteor shower in early May. 

-DDO Defenders 😄

On the evening of July 3^rd, 2020, Richmond Hill resident Ian Shelton captured this image while watching the setting Sun beautifully illuminate the top of a huge distant storm cloud. When sunlight needs to travel horizontally through many additional thicknesses of our atmosphere to reach our eyes or a distant object like the cloud shown here, air molecules can scatter most of the blue sunlight out of the beam, leaving just the yellows, oranges and reds of sunlight to illuminate us or a distant cloud. Contrast this with the unfiltered white sunlight traveling directly through space to reach the Waxing Gibbous Moon seen above and ten thousand times further away than the terrestrial cloud top.

Two days later, Dr. Shelton was joined by several other member of the DDO Defenders to watch the now Full Moon pass into Earth’s shadow. Unlike a more familiar umbral lunar eclipse where a dark circular shadow makes part or all of a Full Moon seem to disappear, a penumbral eclipse is a much more subtle event that is easily missed. Encircling the cone-shaped dark inner “umbral” shadow cast by the Earth is the “penumbra”, a larger outer cone where only partial darkness occurs. On July 5^th, the Moon passed 30% of the way into the penumbral cone, causing only about 20% darkening towards the north edge of the Moon.
  By eye, the event went unnoticed. But it was captured photographically, as shown in the image here. A photograph taken just before the eclipse began was subtracted from a photograph taken at mid-eclipse.

-DDO Defenders 🙂

Hi Everyone,

Here is what Comet NEOWISE looked like this morning, July 8th, 2020 (via a camera, not by eye). The image was processed to increase the contrast and darken the sky, which was already getting pretty bright when the comet finally came out from behind the clouds at 4:30 am. The comet is likely going to remain an easy target for cameras on a tripod for the next week or two, as it moves further away from the Sun and closer to Earth. If the sky is clear, it should be visible by eye if you observe between ~4:00 and 4:30 am. Binoculars should reveal its stubby tail. The animation below shows where to look for the comet. And at 4:30 am on July 9th, 2020, the ISS will be seen passing through the same part of the sky (weather permitting). 

-DDO Defenders

This snap-shot of Venus was taken using a telescope in full daylight on June 7th, 2020, just a few days after Venus appeared to pass just below the Sun*. The planet was just a whisper-thin crescent on this date, with just 0.3% of its illuminated hemisphere visible. It’s during these “inferior conjunctions” that Venus looks biggest to us, because this is when Earth is passing closest to Venus. But Venus still appears at least 30 times smaller than the Full Moon.

One clear difference between seeing a thin crescent Venus through a telescope and seeing a thin (“young”) crescent Moon by eye is that Venus remains very bright, whereas the crescent Moon is much fainter compared to when it is a Full Moon. That’s because we never get to see the surface of Venus, only its very reflective white clouds. In fact, at the time of conjunction, we can catch a glimpse of Venus’ cloudy atmosphere faintly glowing all the way around the planet’s silhouet, making its crescent extend beyond just a half circle like for the Moon. The picture here shows a tiny bit of that extension.

If you want to see Venus for yourself, you will now need to get up just before Sunrise, as Venus has become the Morning Star.

Wishing everyone Clear Skies!

— Dr. Ian Shelton

* Venus was still travelling along its almost circular orbit 50 million km closer than Earth orbits the Sun; but as seen from Earth, Venus was almost perfectly lined up with the Sun 100 million km beyond Venus.