Tag: astronomy

Light-years, Light-minutes and Light-seconds

To quote Douglas Adams… “Space is big. You just won’t believe how vastly, hugely, mind-bogglingly big it is.”

We are accustomed to using miles or kilometers when considering distance. These are the distances that we experience in our everyday lives. Driving to work or the supermarket, we do not travel very far compared to the distances faced by those who study the stars. Those wanting to discuss distances beyond our little planet, the distances to the stars and galaxies face a quandary… The universe is just too big, when using these familiar units the number of zeros become impractical and the numbers cease to be convenient, or even understandable. To express distances in the cosmos, astronomers just need a bigger tape measure.

Andromeda Galaxy
The Andromeda Galaxy, 2.5 million light years away
When expressing distances among the stars we turn to the same phenomena we use to observe the stars, starlight itself. We know that light travels fast, covering huge distances very quickly. Light, just another form of electromagnetic energy, is a universal constant across the universe, how far it travels in a given time is a convenient standard by which to measure the universe.

In a few minutes light travels across our solar system, in a few years it can reach the nearby stars. Thus a distance unit that makes sense in astronomy… The light-year, the distance light travels in a single year. With this we have a convenient unit of distance, one that links the concepts of distance and time. A simple bit of math converts the light-year into familiar units… 9.45 trillion kilometers or 5.86 trillion miles.

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Halloween Sidewalk Astronomy

For many years it has been my tradition to setup a telescope on Halloween. A tradition I have inherited from other amateur astronomers, a tradition I intend to continue.

Princess at the Telescope
A Halloween princess looking through the telescope while we were set up at the King’s Shops
Unfortunately there are few trick-or-treaters in my own neighborhood. We are somewhat at the end of the street and at the top of the hill.

Looking for an alternative to setting up in the driveway, as I have in the past, I instead arranged to setup at the King’s Shops in the resort at the bottom of the hill. The shops make an evening of it, with various entertainment and activities arranged for children and adults. Contacting the Kings Shops management I was able to arrange permission to set up a few telescopes for the evening.

Cliff and Maureen volunteered to join me, bringing more gear. We had a few other club folks drop by. Also helping out were Dean and Melinda Ketelsen, fellow Tucsonans who share the Halloween telescope tradition and happen to be visiting for the week.

Unfortunately clouds hampered us in the early evening. As usual these cleared as the night progressed so that by 8:30pm we had a mostly clear sky. Moonrise provided a beautiful view, followed by Jupiter. There was a steady flow of folks checking out the telescopes. Princesses, Batman, ninjas and more had views of Alberio, Andromeda and other celestial objects. A fun evening for everyone, mixing in just a bit of science education, just what sidewalk astronomy is all about.

Venus Transit Thoughts

Tomorrow we will witness an astronomical spectacle that will not be seen again by anyone currently alive. The gear has been double checked, packed and loaded. Telescopes, cameras and computers are ready, with the exception of a few camera batteries awaiting their turn in the charger.

Imaging Venus in the Daytime
Testing gear for the Transit of Venus.
It is an odd sense of anticipation I feel. I have had the transit marked in my mental calendar for eight years, since I was unable to see the first transit of this pair. I have had a blog post written and scheduled for June 5th, 2012 ever since I moved to the island five years ago. Every time I logged into the administrator page, there it was, at the top of the list, ever so slowly growing closer. That day is here.

After a great deal of work, the gear is ready, a big source of apprehension has been dealt with. There is some doubt about the weather, with both high winds and possible clouds an issue. But there is nothing I can do about that. I can go into tomorrow and have fun with this event. It will be a very long and tiring day at the summit. Whatever happens, it will be a day for memories.

There is a new blog post entered now, for August 17th, 2017, another five years from now. On that day a total solar eclipse will sweep across the Pacific Northwest. We amateur astronomers schedule our lives a bit further ahead than most. I plan to be there.

Astronomy Haiku

You remember haiku? Three lines, the first line with five syllables, a second line with seven syllables, and a last line with five syllables. It may be poetry, but this is easy poetry to write, a short verse with an elegant cadence.

For an AstroDay activity, Keck held an astronomy haiku project. We have a stack of entries we are just now getting a chance to read. Winners are not yet decided, but I have found a few that are wonderful, and worth giving some recognition to.

I should be clear, these are my favorites! Not necessarily the contest winners.

Orion Nebula
NGC1976 or M42, the Great Orion Nebula

Telescopes are great
They make you see very far
I love telescopes
    -Madison Kobayashi (age 9)

Stars shining brightly
I look to them for comfort
In them I find you
    -Lacey Siweila

Lacey is over 18 and not eligible for a prize in the contest. She knew this and enters a poem anyway. You have to love that!

The Moon is so bright
The stars help light up the night
Let’s lay out tonight
    – Micah Timbresa (age 7)

All poems reproduced with permission.

An Evening with Astronomers

A quandry… Our regular astronomy club meeting was the same night as Keck’s evening with astronomers lecture. These invitation events are presented to donors, featuring a lecture from a professional astronomer beneath the palm trees of the Fairmont Orchid resort. A number of our members go to both events and faced a choice of which event to attend.

A solution was proposed… Cancel the club meeting in Waimea and head for the lecture down at the resort instead. To cap the evening we would bring along a few telescopes to share the sky.

The club setup five telescope ranging from Purrcynth’s 80mm refractor to Cliff’s 24″ Dobsonian. It was an impressive line of telescopes. I setup next to Maureen with her new 10″ SCT, a nice match for the 11″ NexStar I use for public work. Arriving before the guests we had a line of telescopes setup and ready for viewing well before dark. As Venus and Jupiter appeared in the sunset we began providing views to the early arriving guests.

Sharing the SkyMaureen sharing her telescope with guests at Keck's Evening with Astronomers

The lecture was presented by Dr. Chris Martin of Caltech, covering a subject that is often overlooked, the environment between the galaxies, vast expanses of space that are anything but empty. Here can be found enormous reservoirs of gas, accounting for the majority of normal matter in the universe, something astronomers call the intergalactic medium.

I enjoyed the lecture. Having a somewhat more than average astronomy education, I find so many public lectures a bit repetitive, I have heard it before. Not this night! Dr. Martin covered a lot of material I had never previously encountered. How the universe is filled with streamers of moving gas, influenced by the gravity of dark matter the gas streams into the galaxies and clusters of galaxies, allowing the formation of new stars in an extraordinarily dynamic process. It was a view that has altered the way I see the universe.

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Keck in Motion Scene Guide

I have been getting a few questions about the video. To answer a few of them I have compiled a guide to the scenes. Some quick explanations to what you are seeing, information on the camera used as well as the exposure information.

The video is a combination of two techniques. Many scenes were filmed as standard video then accelerated during editing to allow the motion to become clear. Examples of this are scenes of telescopes slewing and the interferometer delay lines moving.

Slower subjects, such as clouds or the stars moving across the sky, were photographed as time lapse. Here a large number of still images were taken. These are then processed and converted to video using Photoshop CS5 before loading into the video editing software, Adobe Premiere Elements. To construct the time lapse sequences sometimes required thousands of separate images, quickly filling memory cards and exhausting batteries. After dark it is long exposure time lapse that is used, with individual exposures often 15 seconds to one minute long.

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Astronomy Basics, So Far…

I have completed the first set of the Astronomy Basics posts I intended to do. I really wanted to get these posted as support material for the astro-events posts.

As I finished these I realize I should probably continue and hit a few more subjects. Look forward to a few more Astronomy Basics posts in the coming months.

Meteor Watching

Watching meteors is one of the simplest forms of astronomical observing. Just about anyone can enjoy meteor watching, from just about anywhere in the world. Enjoying the show takes only a couple things… A dark sky and a comfortable place from which to watch.

Leonids in Orion
A pair of Leonid meteors streak through Orion
Meteors are simply small bits of debris hitting the Earth’s atmosphere at very high speed, typically tens of thousands miles per hour. Our solar system is rich with this debris. Most of these bits are quite small, about the size of mote of dust or a grain of sand. Something the size of a pea would create a spectacular fireball that lights up the whole sky. While they often seem close, they are actually quite high, 60 miles (100km) above the ground when they flare into short lived fireworks.

The mechanism for the show is simple. When something hits the very thin air high in our atmosphere at very high speed it compresses the air in front of it. This compression also heats the air, causing it to glow white hot. Heated enough, the air becomes a plasma, the molecules shredded and electrons freed from the atoms. It is not the meteor itself that you see, but the glowing plasma around it.

There are a number of questions many people ask about meteor observing. You can find many of the answers below. Watching a meteor shower takes no special equipment, expert knowledge or extravagant preparation. This is an activity nearly anyone can enjoy, one of the spectacles of nature available to all.

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Lunar Apogee and Perigee

Does the Moon seem a little larger and brighter than usual? It may not be an illusion, sometimes the Moon really does look a little larger or smaller in the sky.

Like all orbiting objects, the Moon does not orbit in a perfect circle, but rather in an ellipse. This means that as it orbits it is a little further away or a little closer. In the case of the Moon the difference is not much, but you can see it, if you know to look.

Lunar Apogee & Perigee
The apparent size of the moon as seen at perigee versus apogee
When the Moon is furthest from the Earth, a point called apogee, it will be about 405,000km (251,000miles) from the Earth. While at perigee, the Moon will be about 360,000km (223,000miles) from the Earth, as measured from the center of the Earth to the center of the Moon. The change in distance leads to a noticeable difference in the size of the Moon as seen by an observer here on Earth. When at perigee the moon will appear about 12% larger than when seen at apogee.

Lunar Month Animation
Click to view a simulation of a lunar month showing phase, libration (tilt), and the size change as the Moon goes from apogee to perigee. Image credit Tomruen via Wikimedia Commons
The difference is most noticeable at full Moon. If the full Moon occurs near apogee or perigee, an experienced skywatcher can spot the difference. The effect should not be confused with the well known Moon illusion, where the Moon can appear larger near the horizon.

The period of time between full Moons, the synodic month, is about 29.5 days. While lunar perigee occurs every 27.5 days, an anomalistic month. Since these periods are not equal, the cycle drifts in and out of phase. About once a year the cycles coincide and full Moon and apogee or perigee will occur near the same time.

At apogee, the Moon will be appear about 29 arc-minutes in size, a little less than half a degree. At perigee the Moon will be about 33 arc-minutes across, a bit more than half a degree. The numbers may not seem like much, but it is a visible difference. The simulated images shown here will give a better idea of what the numbers represent.

This change in size and distance leads to the moonlight being a bit brighter at perigee than at apogee, about a 30% difference. So if that moonlit night seems brighter than you remember it may actually be the case.