FirstLight Astronomy Club

33°29.6'N / 117°06.8'W / 1190 ft.

Moon taking us on a tour

occult_mars
In the next few weeks the Moon is going to take us on a tour - a tour of all the visible planets. So check your bags, confirm your seats, and mark your calendars - we are ready to go.

Our first stop is on the evening of the 22nd and will be the most difficult to see of all our sites. A very young crescent moon will immediately follow the sun as it sets. If you can manage to see that moon right around 6 o'clock near the horizon, you may also be able to just make out tiny Mercury to the left of it. Kudos to you if you can see both! Next stop: Venus!

On Saturday, the 25th, the now easily-spotted crescent moon will appear parked near bright Venus. Venus has been rising in the early evening skies over the last months as it swings around the sun. Right now it is at a point in its orbit where its cloudy skies reflect the most light it can towards us - Venus is at its brightest.

Just one evening later - on the 26th - the Moon is now cozying up to our big brother planet out there, Jupiter. Because of the way our orbit around the sun combines with Jupiter's, the gas giant will be descending in the skies now, appearing to get closer and closer to the sun over the next weeks. Venus will continue to nudge higher as Jupiter goes lower and they will pass each other around March 13.

Now our next stop isn't for more than a week. In the meantime, relax and daily observe how the moon goes from crescent to first quarter, then to full.

When it reaches full - on March 7th - it is then that our favorite satellite reaches Mars, rising in the early evening over in the east. Mars will be the slightly pinkish dot a little higher and to the left of the full moon. It is about the same distance from the moon as the width of your fist held at arm's length. Mars is now near "opposition," meaning it is on the opposite side of the earth as the sun is.

We are now headed for our last stop on the Lunar Express. This will require you to stay up a bit later than early evening. On March 10th, more than two weeks after we started our tour, the now waxing gibbous moon has finally made it over to Saturn. Around 10 o'clock, both of them will rise in the east. Saturn will be a tiny golden dot slightly higher and to the left of the Moon. Of course, through the telescope Saturn is a thing of ringed beauty. See it if you can.

So what have we seen in the last couple weeks? Nothing less than Mercury, Venus, Mars, Jupiter, and Saturn - the great planets of antiquity. And our obliging Moon, going through its phases as an added attraction, has taken us through it all.

Vesto Slipher

slipher
There are a lot of absolutely astounding things about the universe that have been discovered in the last century. I mean truly awesome. Things like realizing the Milky Way is not all there is, that we are in an unfathomably big place, that it all has a finite age, that we don't know what most of the universe is made of, that we are not only expanding but actually expanding faster and faster! It makes the head spin.

But all of these ideas did not just pop up out of a vacuum. They came from very driven and intelligent people who wanted to find out how the Whole Shebang works, and their efforts have given us a richer view of this already abundantly rich cosmos. Let me give you one example of what I mean.

Back in the 19th century the prevalent worldview of the universe was that we lived in a pretty big star system that has always been here. There were no other galaxies, no inconceivable vastness, no creation event long ago. What we saw was all there was and it was all confined to a relatively small space.

But then along came a young American astronomer, Vesto Slipher, from Lowell Observatory who, in the 1910's, seeded astronomy with some disturbing facts.

Slipher observed objects in the heavens called spiral nebulae - cloudy objects, spiral in shape. That was nothing new in itself. What he noticed was that they were moving in very unexpected ways.

Now what most people back then believed was that things in the sky - stars and these nebulae things - should be moving slowly and randomly about in every direction. But these objects were not obeying that belief. Almost all of nebulae things were moving away from us. And they were moving away quickly. There was nothing random about it.

What are these objects really? Could it be that they were very distant galaxies in and of themselves? Was the universe way bigger than anyone had ever thought? And why are they almost all moving away, and very quickly? Something strange was going on.

It was only a decade later, in the 1920's, that Edwin Hubble and Milton Humason added some important facts to Slipher's work. Those spiral nebulae were really entire galaxies, not local clouds. They were far away - and huge.

Our star system was not "all there was."

And not only were most of these galaxies moving away from us, but the farther away they were, the faster they were moving away.

What phenomena could possibly explain that? An expanding universe, that's what. These men, almost a century ago, bucking tradition, deduced that we live in a monstrously big and expanding universe, a discovery that would drastically change the face of astronomy. And this expanding universe phenomenon would lead to the idea of a beginning to it all, a profoundly philosophical claim.

In future columns I will cover more discoveries by daring men and women astronomers, discoveries that have completely changed the way we see the cosmos.
Temecula Valley High School / Temecula, CA · Some images © Gemini Observatory/AURA Contact Me