Observing with Street Lights

Observing with Street Lights
Dark sky sites not always necessary to see the Milky Way (This image was taken ouside of a B&B in Julian, CA)

Saturday, June 26, 2021

Moon setting and rising on the horizon; Drawworks arrive in Boca Chica; Space Elevator at ISDC 2021; Amateur Spectroscopy tutorial at next AAVSO meeting; Let's go to Antarctica in 2022!

 Greetings from Palmia Observatory

Well ever since being reminded of the moon rising over the lighthouse, as discussed in the June 22 post, we have been looking for similar situations to show the apparent size of the moon and now have had some modest success. Also a part of our email housekeeping chore, you can now sign up for new website posts when they are released at: Palmiaobservatory+subscribe@groups.io

The first attempt was with the setting moon in the morning.  In this case we found a location where we had a view of the horizon, such as it was will hills and some towers on it.  The risk here was if the morning sky would be too bright.  The lunar phase is just a day or two passed full moon, but the moon is still quite bright and nearly full.  In this 300mm DSLR image you can see the moon just 2 degrees above the horizon at 6:18 am and the sky is quite bright.  The path of the moon looks to be going down near the trees, and not the hoped for transmission tower at the bottom right.  At the same time, we have a dust bunny in the upper left.

Moon setting at 2 degrees above horizon at 6:18 am PDT, 300mm, 1/1000 second (Source: Palmia Observatory)
Moon setting at 2 degrees above horizon at 6:18 am PDT, 300mm, 1/1000 second (Source: Palmia Observatory)


When the moon got down to just 1 degree from the horizon, the sky was getting so bright and thin clouds were starting to interfere with seeing anything.

Bright daylight at 1 degree above horizon, 300mm, 1/1000 second (Source: Palmia Observatory)
Bright daylight at 1 degree above horizon, 300mm, 1/1000 second (Source: Palmia Observatory)


Ok, so the morning adventure didn't work out too well, but lucky for the observers out there, the moon set to rise again that evening at around 9:40 pm PDT.  So we had to scout around and find a view of the horizon, this time not facing the southeast, but now facing the southwest.  In this 300mm DSLR we see the moon braking out above some nearby trees in the foreground.

Moon rise at 9:47 PDT, 300mm, 1/15 second (Source: Palmia Observatory)
Moon rise at 9:47 pm PDT, 300mm, 1/15 second (Source: Palmia Observatory)


We can increase the exposure time from 1/15 second to something in the range of 2 seconds, which will bring out the background while overexposing the moon at the same time.  Hey, luckily there was a electric transmission line tower very close to the moon in this shot.

Recall from the trigonometry discussed in the post of June 22, we expected a 200 foot tall tower to extend an angle of 30 arc minutes, just like the typical size of the moon.  In this case here, if we assume the tower is 200 feet tall, and by counting pixels it appears about 30%  bigger than the moon, we expect to find that we are only about 3 miles away from the tower, not the 4 miles needed for the tower to appear as the same size as the moon.

Moon rise at 9:47 PDT, 300mm, 2 second exposure (Source: Palmia Observatory)


Now with the moon higher in the sky we can take another shot, this time with just 1/15 second exposure to bring out some of the features of the moon.

Moon rising above horizon at 9:47 pm PDT, 300mm, 1/15 second (Source: Palmia Observatory)
Moon rising above horizon at 9:47 pm PDT, 300mm, 1/15 second (Source: Palmia Observatory)



So, at least we had some modest success in finding locations within the city where we could get some near horizon view of the moon setting and rising.  In other space related news we find the work on the SpaceX Starship Orbital Launch tower just keep on making progress.  Here in this tweet from NASASpaceflight.com we we the arrival in Boca Chica some heaving mechanical lifting equipment.  This drawworks will be installed on the Launch Tower and supposedly will be use to lift the Starship and Heavy Booster into position.  It is like this equipment will take the place of the crane now used to lift Starships from their transport vehicles to the launch pad.

Drawworks for Starship Orbital Launch Tower arrives in Boca Chica (Source: NASA Spaceflight.com)Drawworks for Starship Orbital Launch Tower arrives in Boca Chica (Source: NASA Spaceflight.com)
Drawworks for Starship Orbital Launch Tower arrives in Boca Chica (Source: NASA Spaceflight.com)

If you are not familiar with mechanical systems like the drawworks, check out this concept sketch showing how the drawworks is used in oil derricks to raise and lower the drill string in and out of the well bore.  The speed and lifting capability are functions of the speed of motors controller the fastline and also on the number of times the line is circled around the crown block and the traveling block.  We won't have to wait much longer until the whole orbital launch complex is ready for the first orbital flight from Boca Chica.  Yeah!

Get ready for your cruise to Antarctica in October 2022 (Source: www.poseidonexpeditions.com)
Concept drawing of drawworks as used in oil rigs (Source: Transocean)

In other space related news, the International Space Development Conference (ISDC)  2021, is holding their annual meeting online this time, but is supposed to be in person next year in Arlington, VA.  There have been some interesting presentations, but for now I can comment about another interesting concept, having to do with how to get into space, without relying on the rocket equation, and that is the "space elevator."  In this screen shot, Peter Swan describes some of the latest development work going on in the space elevator field.  Peter says that the material with which to fabricate the cable now seems to available.  He hopes to have the space elevator available for deployment in the 2030+ timeframe.  The space elevator is described as the "Green Road to Space" because it can be powered by renewable electric energy.  He see ultimately three separate space elevators, all located on the equator and equally spaced around the globe.  We will have to wait and see.

Drawworks for Starship Orbital Launch Tower arrives in Boca Chica (Source: NASA Spaceflight.com)
Continuing development of space elevator concept (Source: Peter Swan, ISDC

If you have forgotten some of the details of the space elevator concept check out the diagram below.  The elevator cable is stretched between some point on the equator and another point up beyond the geostationary orbit altitude, where the counterweight is positioned.  The force felt by the cable and associated climber is a function of both gravitational attraction and centrifugal force.  Remember that the cable continuously moves at constant rotary speed as the Earth rotates, so that the counterweight is always directly above the same point on the Earth.  The tension in the cable varies with altitude and a key design parameter is to vary the tapering, or diameter of the cable, to match the changing force needed at any particular altitude.  At the geostationary altitude, the tension can be close to zero, just as it is theoretically zero at the surface of the Earth.

The counterweight is not in a freefall orbit.  The speed of the counterweight is much faster than needed for an orbit and it is this extra speed that creates the centrifugal force in the cable to keep the cable taut, which prevents the counterweight from flying off into space.

The concept is called the green road to space because electricity can be beamed up to the climber, which has motors attached to the cable and pulls the cargo up the cable.

Right away we see that the construction of the elevator needs to include transporting the counterweight to the required altitude and then reeling out the cable and keeping it attached all the time. Rockets are going to be needed for this first construction in space.   It just seems there are a lot of problems that need to be solved just to get the elevator in position.  But if new materials have already been discovered to make the cable, then maybe the rest of the effort is just a lot of engineering.

Space elevator concept with cable and counterweight (Source: Wikipedia)
Space elevator concept with cable and counterweight (Source: Wikipedia)


Finally we have some new meeting on the calendar that might be applicable to physicist wannabes and amateur astronomers who want to get more involved with amateur spectroscopy.  I definitely have an interest in this and the AAVSO is sponsoring a spectroscopy tutorial that occurs just before their 109th annual meeting in November, 2021, and will be conducted in person in the Boston area.  Hope to see many of you there!

Get your plans in place to attend the 109th AAVSO Meeting (Source: www.aavso.org)
Get your plans in place to attend the 109th AAVSO Meeting (Source: www.aavso.org)

Finally, as long as we are looking at future travel plans, and as we continue packing our bags for our cruise around Iceland next week, let's look further into the future and consider including a cruise to Antarctica in October 2022.  It looks like a real adventure and a lot of fun.  Remember the name of the cruise is Poseidon Expeditions, not "The Poseidon Adventure."  See you all there!

Get ready for your cruise to Antarctica in October 2022 (Source: www.poseidonexpeditions.com)
Get ready for your cruise to Antarctica in October 2022 (Source: www.poseidonexpeditions.com)


Until next time,


Resident Astronomer George



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