January 26, 2020 – Let There be Dust

It’s everywhere, except maybe in super clean rooms where the air is constantly filtered.  Dust mostly comes from the breakdown of bigger stuff like rocks, planets, stars, people, pets.

Nancy and I live with a dust machine.  Her name is Blanca and she (we’re not really sure about that) makes dust.  Oh, Blanca is a Cockatoo.  She makes enough dust to clog a nearby oscillating fan’s filter in three days.  If I use the fan anywhere else, it lasts a couple of weeks before the filter needs cleaning.  That’s dust!

Dust is pervasive in our universe.  I don’t know if anyone has estimated how much dust exists in the universe, a web lookup just brings up particles, like electrons, protons, neutrons, quarks, etc.  The density of dust in our universe does vary and there are places where it’s cleaner than a clean room, with maybe only one grain of dust per cubic kilometer.  There are other places where dust is more densely concentrated.  One of those places is the inner solar system, home of rocky planets Mercury, Venus, Earth, and Mars.  Dust gets concentrated in flat bands along planetary orbits.

Where does dust come from?  As I mentioned in my opening, it comes from the breakdown of larger objects.  We can thank aging red giant stars for silicate and very, very old red dwarf stars for carbon.  These are the most common core materials in extraterrestrial dust.  Once they precipitate out of the star’s atmospheres other molecules can attach and voila, dust.  Of course, it’s more complicated but you get the drift.  As dust particles merge gravity comes into play and we get pebbles, rocks, asteroids, comets, dwarf planets, planets.  They all break down via collision, stellar wind, cosmic radiation, atmospheric or hydrological effects, and we get dust again.  Dust to dust.

Most everything that we can detect is star stuff and dust is simply a transitional phase.

Dust is kind of yin-yang when it comes to astronomy.  The yin is how dust obscures the view of some distant objects, such as those toward the center of our Milky Way galaxy.  There is a lot of dust between us and our galaxy’s central area.  Optical telescopes are useless.  We must resort to radio/microwave, and infrared telescopes to get a glimpse there.  They see through dust.

Then there’s the yang.  Comet’s tails are made of dust and are beautiful to see.  We get meteor showers from them too.   Another dusty treat is called the zodiacal light.  The zodiacal light is most visible during spring after sunset, and autumn before sunrise.  February 10-24 will be optimal for evening looks.  Find a spot where the horizon is mostly visible and look to the west after evening twilight has faded.  Look for a cone-shaped glow rising from the horizon.  That’s extraterrestrial dust reflecting sunlight.

What’s in the Sky?

January 26-28; evening; southwest:  Mercury, a crescent Moon, and Venus share the sky.