Plano Public Library Questions Answered

This post is to give answers to all the questions posted in the chat window at the July 25th 11AM Question and Answer session with the Plano Public Library:

  1. Question: How many years has Les Murry been working for NASA?
    Answer: While I would LOVE to work for NASA, I do not work for NASA and I am just a NASA volunteer and am trained by NASA to do outreach and inform the public of ongoing missions at NASA and the science being produced by NASA. NASA has many great resources for STEM education! I have a degree in Physics and Computer Science and in my day job I work on high speed data networking and optics.
  2. Question: There was a question about the best telescope to buy.
    Answer: The first thing I would recommend is to get a set of binoculars, perhaps a set of 7×42, 8×42 or 10x30s. Any larger than that and they get too hard to hand hold and get very shaky when observing astronomical targets. Under dark skies you can see hundreds of interesting targets just with binoculars. You can get a really good pair for $100 to $200. Look for ED Glass (Extra Low Dispersion) and anti-reflective coatings are good.

    As for telescopes, the one driving requirement is a steady mount. Many are on flimsy mounts that will just frustrate you and drive you away from Astronomy. I recommend as a starting scope, a tabletop dobsonian. They are inexpensive and do quite a good job for the money. They are reflectors which give you the best size to price ratio and are wide field making it easier to find targets. There are several manufactuers tha make these at very reasonable prices.

To the left is the Orion starblast which is about $200 and works very well.
https://www.telescope.com/catalog/product.jsp?productId=130921&src=row2col1-prodtitle
A neat option is the Astronomers without Borders scope which 50% of the price is donated to send telescopes to the developing world. It is about the best bargain for the price.
https://shop.astronomerswithoutborders.org/products/awb-onesky-reflector-telescope
A really inexpensive but serviceable scope coming in at about $50 is the Celestron Firstscope.
https://www.celestron.com/products/firstscope-signature-series-moon-by-robert-reeves-telescope

The old used Edmund Scientific Astroscan can be found on the internet in the $125 range and are great for kids as they are almost indestructible and have wide views and let kids explore on their own with little to no fear. There was also the portaball which was similar.

3. Question: Paraphrasing(What magnification do you need to see the moon?
Answer: Usually about a minimum of 50x is needed to see the whole moon mostly filling the eyepiece. To see a lot of the features of the moon, you typically need about 150x or so. Usually a 25mm, 15mm and 10mm eyepiece with a 2x or 3x barlow lens give you the views you need. You get magnification by dividing the telescope aperture by the focal length of the lens. i.e. for starblast, it is 450mm / 25mm =18x magnification,
450mm / 10mm = 45, with a 3x barlow = 45 x 3 = 135x

4. Question: Where can I go to see the comet? (Or do stargazing around Dallas?)
Answer: Due to all the light pollution in Dallas, it is very hard to spot the comet even with binoculars even if you know where it is. It is impossible to see naked eye within the city. Under dark skies, it is very clearly visible to the naked eye. You really need darker skies to see it well. The best locations near Dallas with the shortest drive tend to be to the North East or North West of Plano. Here are some sites I visit to do viewing:
Lake Ray Roberts State Park – While not great, the skies are darker than much of the metroplex and it is a good compromise.
https://tpwd.texas.gov/state-parks/ray-roberts-lake

The LBJ grasslands is pretty good for stargazing. There is a national forest campground, $5 per night per car at the Black Creek Recreation area.
https://www.fs.usda.gov/recarea/texas/recarea/?recid=30232

Mineral Wells State Park is pretty good and is not too far from the city.
https://tpwd.texas.gov/state-parks/lake-mineral-wells

A good place that is currently closed, but in nonCovid times is the Rafes Urban Astronomy Center. It is currently closed, but typically has monthly star parties and allows the public to look through their telescopes. It is a great family outing. Lets hope for a Covid vaccine soon!

5. Question: Why can you see the Milky Way from Earth if you live in it???

When we see the Milky Way stretched across the sky, we are looking into the heart or the core of the Milky Way. We are located in the Orion Arm along with the stars of the Orion constellation and many more. When we look inward towards the core, we are seeing the stars in the next arm over, the Sagitarius arm and then on inward to the galactic center.

The darker areas or “dark lanes” are actually dust that is blocking our view to the core so that we only see the foreground stars between us and the dust.We are seeing the Milky way edge on. There are so many more stars to see because the star density in the core is much higher at about .013 light years apart vs about 5 light years out where we are.

6. Question: What iPhone app do you suggest we use for star gazing?
Answer: Here are some Apps that I like that help you get the most out of star gazing.

Star Charts is a great freeware star charting program. It supports showing you what is up in the sky using augmented reality, has notifications of upcoming stellar events.

The NASA App allows you to watch NASA TV, get a live view from the ISS, see ISS passes for your location, etc. It is a great way to keep up to date on NASA. You can also listen to third rock radio which is an Alternative Rock station.

7. Question: I heard plans of new horizons flying to the closest solar system. Will this take place?

Answer: I’m not aware of any plans to do this and it would be more of a symbolic guesture. It would take 78,229 years to reach Proxima Centari at its current velocity. Also there isn’t enough fuel to accurately guide it so most likely it would miss by a wide margin. We can possibly point it in the general direction of a target star and hope. The more likely follow on mission is to try to find Kuiper belt or Oort Cloud objects to find.

8. Question: what makes the beige color for Pluto’s heart?

Pluto’s Heart

Answer: Pluto’s icy heart is made from an ice cap made of Nitrogen ices. At least one mode suggests tha with Pluto’s 120 degree axial tilt any small deposit of ices that are reflective tend to keep the area code and attract more ices to deposit there and they tend to build up. The weight of the ice may also have caused it to sink which would explain why Sputnik Planitia is lower than the surrounding area. 98% of the ice on the surface of Pluto is Nitrogen ices with traces of Methane and Carbon Monoxide. I couldn’t find any information on the colors. Look here for more info: https://www.nasa.gov/feature/scientists-probe-mystery-of-pluto-s-icy-heart

9. Question: Why do stars rise and set about 4 minutes earlier each day?
Answer: It takes 365 days to go around the sun so roughly about 1 degree of its orbit. That means that the Earth has to turn 1 degree less than 360 degrees to face the sun again. This one degree equates to 4 minutes of time. (1440 minutes per day / 360 degrees says 1 degree equals 4 minutes). One revolution with respect to the sun is a solar day. One rotation with respect to the stars is a Sidereal day. You can get more information about this here: http://www.astronomy.ohio-state.edu/~peterson/Ast291/Lectures/FoAchapter01.pdf


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