Feb 12, 2020


I’ve always wondered how a galaxy could be more than 27 billion light years from Earth when the universe is roughly only 13.7 billion years old. A light year is considered a unit of distance and indicates how far you can go in one year at the speed of light (about 9 trillion kilometers). It doesn’t seem right that something 27 million light years away can be that distance when it has had only 13.7 billion years to go that far. Actually there are 2 reasons that explain this seeming inconsistency. One reason is that the universe is not fixed in size in space. The universe is expanding and, as I mentioned in a previous column, it is increasing its rate of expansion as time passes. Over time, the galaxies are moving away from each other as space expands. Yes, galaxies collide but these are localized phenomena that occur when they are near enough for their respective gravitational fields to interact and attract each other. The second reason is that a galaxy 27 light years away is not being directly measured. We are seeing light from that galaxy that is ancient. Its light has been traveling for billions of years through the universe. When the universe was younger, the universe was smaller and that light had a shorter path to travel. It only took a few billion years to reach us. In the mean time, the universe has expanded. The distance between that galaxy and us is much more. So much so that if that light were to make the trip today, it would take 27 billion years to reach us and would not be observable. Astronomers, with the understanding of the changing nature of the universe, can predict that that 27 billion light year distance is based on light that set out long, long ago.

It’s that time of year for the Zodiacal light! Its cone shaped glow will be best viewable above the western horizon from mid February through early March after twilight has faded. The triangular shape of the light, with its apex pointed towards the zenith, is caused by the debris disk of our solar system. Its radiance is light glinting off of that cloud of particles. The disk of dust ranges through the inner solar system and extends out from the Sun to the orbit of Jupiter. The debris originates from comets and material thrown off by asteroid collisions. The dust particles have a size range from about a few micrometers to a few centimeters. The debris mainly orbits in the ecliptic plane – the plane in which the planets travel around the solar system. Therefore the best time to observe its glow is when the axis of the Earth’s rotation is tilted at a maximum to the ecliptic plane. This occurs around the time of the spring and autumnal equinoxes. At the spring equinox (February-March), it will appear about an hour after sunset on the western horizon. At the time of the autumnal equinox (September-October), it will present itself before dawn on the eastern horizon. Ancient astronomers called it the ‘wings of the morning’ because when it appeared in the fall at sunrise, it signaled the dawn. The best time to view the Zodiacal light is an hour or 2 after the Sun has gone down. Find yourself a nice dark site when the Moon isn’t around. Dress warmly (need I say), let your eyes get dark adjusted and look to the west.

In the evening sky this month Mercury can be seen in the west and bright Venus is hard to miss in the west as well. Mars, Jupiter and Saturn can be made out in the southwest in the early morning. They are an exceptionally fine sight about an hour before sunrise on February 29th about 10 to 15 degrees above the horizon. Just before dawn on the 18th, a thin crescent Moon passes in front of Mars.

Monthly Highlights:

All Month: Zodiacal Light.

Feb. 9th: Full Moon. This one is called the Full Snow Moon. It’s the snowiest month of winter and I would hazard a guess that the name suits. It’s also called the Full Hunger Moon when game was very hard to find.

Feb. 10th: The Moon is at perigee (closest to Earth) – 358,360 kilometers.

Feb. 15th: Last quarter Moon.

Feb. 18th: The Moon passes about a degree north of the Mars.

Feb. 19th: The Moon passes about a degree south of Jupiter.

Feb. 20th: The Moon passes about 2 degrees south of Saturn.

Feb. 23rd: New Moon.

Feb. 26th: The Moon is at apogee (farthest from the Earth) – 403,920 kilometers.

Feb. 27th: The Moon passes 6 degrees south of Venus.

Feb. 29th: Mars, Jupiter and Saturn make a beautiful display above the southwestern horizon about an hour before sunrise.

That’s a wrap. Keep looking up! And don’t forget Jupiter and her dancing moons – Callisto, Io, Europa and Ganymede in the early morning!

“The Beginner’s Observing Guide by Leo Enright is an invaluable companion for adventures in the sky. It also contains useful star charts. It can be ordered from the Royal Astronomical Society of Canada at www.rasc.ca/publications. A subscription to our very own excellent Canadian astronomy magazine “SkyNews” can be arranged at the RASC website as well.

Let me know how your observing has gone this month, especially anything unusual. I enjoy the feedback. If you have any questions or suggestions you can contact me through this paper or email me at This email address is being protected from spambots. You need JavaScript enabled to view it. . Clear Skies! Fred.

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