Friday, 30 June 2017

Just how fast do you need to go?

This question has come up more than once recently. And from some pretty strange sources. If someone wanted to view the eclipse from the west coast to the east coast, how fast do you need to go? There are those that have access to aircraft and wondered if it was possible to keep up with the shadow of the Moon as it raced across the continent from Oregon to South Carolina.

As a quick answer, you need to go pretty fast. Like in the range of 1400 to 2400 MPH. That is pretty fast. Supersonic!

The average overall speed would be just over 1600 MHP based on a distance of around 2500 miles in about an hour and a half. At first the speed would be higher, in the 2400 MPH range. That is because the shadow is hitting at an angle. It is more oblong in shape (like a football) but that doesn't matter much because we need to keep up with it. The shadow speed slows as the eclipse reaches the part of the globe that sticks out the most, near Illinois/Kentucky/Tennessee. At that point it is "only" doing about 1400 MPH.

Is there an aircraft that can do it?

Turns out yes, there are several aircraft that might have a chance. The problem is how far can they run at that speed. Most might need to slow way down to fuel up the tanks and by then the shadow has out run them.

In 1973 a prototype of the SST Concorde raced the shadow of the Moon across Africa. It was able to keep up for an astounding 74 minutes before breaking off. The thing is, there are no windows looking up from the Concorde, just a small area for instruments to be placed. They could see out the window, not the eclipse, but the shadow sweeping over the land below.

What about those super spy planes, can't they go that fast? Again, they can but not for long. They go even faster otherwise they might burn up the fuel too quickly. So while they can run at the speed for a short while they would either have to slow down and fuel up or jump way ahead and make a loop about the shadow thus not staying under it the whole time.

14 or 12 states?

If one wanted to see the eclipse from every state that touches the umbra the problem is one of geometry. Up in the air you are outside of the shadow! It is hitting the Earth at a slight angle and is shifted to the South the higher up you go. For 2 of the 14 states the umbra makes a glancing blow at surface level - but not up where the jets fly! I suppose now we need to see what states to the south of the central path might need to be added to the list of states crossed at jet elevations....

Thursday, 29 June 2017

Planning your eclipse day

It seems every journalist in the USA is taking a stab at writing a piece about solar eclipses. This is great! Finally we get to tell the story. You see, a total solar eclipse is an experience.

  • For some it starts years before the actual event. They are considered the eclipse chasers
  • For some it is just like any other day. They are innocent by standers
  • For the rest it is another day on vacation with an eclipse chaser. They are groupies.

I am writing this blog entry is for the eclipse groupies.

This is kind of what it will be like to experience your first eclipse in the company of an eclipse chaser.

Morning, sunrise:

Eclipse chasers have been frantic about weather and other secret contingency planning. They probably did not sleep the night before. Chances are good that this will be the first time you are actually looking at the weather with any real concern. You are wondering whether or not it will cooperate during the solar eclipse. The sleep deprived chasers will be the first clue. If they are frantically loading up to move, you should join in and help - after you have some breakfast and coffee maybe.

But let us assume the location is deemed good and proper so there will be no moving to a new one in the early hours. Now you can sit back and watch the dance of the eclipse chasers.

If the eclipse is in the morning, before noon, then the eclipse chasers have been set up since sunrise (if not hours earlier). 

If the eclipse is in the afternoon, then the eclipse chasers have been set up since shortly after sunrise (if not hours earlier). 

Generally the eclipse chasers will stake out an area to view the eclipse, sometimes days in advance. The location may be marked with tape or a small sign. Most will wait until eclipse day with the most concerned members being up early and putting up tripods or other equipment to define a boundary.

They will choose a location based on many reasons. Some want the landscape view, others want an unobstructed view, some want specific silhouettes visible, while others choose a space way bigger than they need so they can select who sets up near them. Other considerations may be a desire to be near a scarce resource like electrical power or to best observe shadow bands. What ever the reason, most will follow where ever the more experienced eclipse chasers in the group locate so they can see what they are supposed to do. They also like to be near the expert so they can ask questions should something come up (at this time it is either equipment set up or camera related).

First Contact:

First contact has a big build up with little to actually see. The Moon is just starting to cover the Sun. It is just a small arc of darkness against the edge of the Sun. You cannot see it with the solar glasses right away, the Sun will still look like a ball. But give it a few seconds and the anomaly will begin to appear. It will slowly grow covering the solar disk over the next hour.

Over the next hour each time you check the Sun with a viewer a through a solar telescope, more and more of the Sun is covered by the Moon. For most this eclipsing process seems to take a lot longer than needed. Kind of like waiting for anything, time just runs slower when you watch it carefully. Should you have the ability to completely ignore the partial eclipse phase you will not really notice much until the Sun is about half covered. The temperature may start to dip and the light of the Sun is starting to seem odd. It is not as bright as it should be (on a clear sunny day). You will hear eclipse chasers remark about the temperature at some time. If you don't have a light shirt or cover up of some type, now is a good time to consider getting one. The eclipse is still half an hour away and that may seem like eternity to eclipse chasers, it really isn't and thus a good time to get ready for the next parts.

As the total eclipse draws near the eclipse chasers will caution others not to move or jump around, a buzz will start as people say they see darkening on the horizon to the West or they spot shadow bands. Shadow bands are waves of light and dark that sweep across the surface making seem as if the ground or a wall is vibrating in light. They are kind of hard to see if you are not at the right angle.

Venus and other brighter planets may become visible at this time. The sky takes on a darker blue color similar to a clear sunset. You should notice the air feeling cooler and maybe the wind settling down.

Second contact:

With just seconds remaining the buzz of noise from your group will increase until there is a scream of joy or amazement and others yell out second contact. My advice is to wait another couple seconds before looking at the eclipse. The diamond ring at second contact will flash blind you and cause spots to appear in your field of vision. Much like a bright flash camera going off in your face, and having that happen right at the start of totality is really poor timing.

Looking up at the eclipse is amazing. An eye in the sky, a bright flower with a dark center, an angel, the open yaw of a dragon falling on you from above, and much more have been used to try to describe the view.

It does not matter once you have seen one. You are now part of that special group.

After Totality:

You have lost your eclipse virginity and are no longer a groupie. Now you know. There is a good chance some of you just might become eclipse chasers.

After totality there will be a celebration and much discussion about what was just seen. Pictures will be compared and shared. And plans will begin in earnest about the next one. It seems strange, but most will ignore the eclipse ending. Watching the Moon slip away and the Sun grow can be a very sad for eclipse chasers. It means another eclipse is over and it will be a while before they can see that amazing thing in the sky again.

- Wishing you have clear sky above your head for the eclipse in August!

Friday, 9 June 2017

There will be how many people?

Michael Zeiler has been "playing around" with the GIS tools from ESRI (where he works, so it really isn't playing around per se). He has put together some awesome eclipse maps from the databases they have available for population, traffic, and so forth to predict how many people could show up for the eclipse at various locations.

Click here for The Great American Eclipse analysis.

These tools can be used for city and state planners to help anticipate the best and worst case scenarios in terms of visitor counts. Emergency response could be impaired in some cases and it is not a bad idea to pre stage responders in some places.

For eclipse chasers these tools show that the highways could become full of cars going to or leaving after the eclipse. The chances are greater that traffic jams will happen after the eclipse as everyone decides to head home about the same time.

I suppose it is handy to have a GPS or at least some good maps of the back roads just in case!

Fred Espenak has a road atlas that could prove quite useful if the local Internet resources are stressed.

Saturday, 3 June 2017

Doomsday Eclipse Prophesy?

I was looking at some eclipse videos on YouTube and ran across a large selection where the eclipse coming in August is considered a sign from God about the end of the world. It seems that there is a population of people greatly concerned about it. These sites get a lot of views. Are people really believing what they say, or is it just a source of amusement as it was for me at first.

Rest assured, the eclipse is not a sign that the world is ending. It is a celestial event that is worth seeing and really beautiful. Where these folks got the idea that it signified something special is from the deep past, when mankind did not have a grasp on the workings of the solar system and heavens above. Today we have a grasp. We know what causes eclipses. We know about planetary movements. We can predict these things with great accuracy because we have figured this stuff out.

So just where do these folks come up with these ideas? One thing I found in common is that they all want to sell books and subscriptions to hear more of their "wisdom". And I observed that these supposedly good people see no problem in stealing images from websites and other sources in their productions (with absolutely no credit). They abuse copyrights and trademarks, operating outside the common practices of good journalism. As a result I am very skeptical about the motives. I think they are a bunch of hustlers trying to con people out of their money and time. So do not buy the books and do not send them money, just ignore their pleas for support.

Just as a side comment I also noted that there seems to be concern about some mystical planet coming by that will cause all sorts of problems. Some of the dates of destruction have come and gone yet the same people keep on spewing this trash. It really amazes me how seemingly credible sources are willing to play along. Or are they? Many of the quotes and video clips were taken out of context, a common tool of the fake-media.

While I am big fan of free video on YouTube I do find such nonsense distasteful and worthless. All I can say is that if you encountered my blog while searching for eclipse doomsday predictions, forget it. No doom, just a great show, hope the sky is clear for you to see it.

2012 Total Solar Eclipse by Denise Kramer