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Wednesday, April 4th 7:00 pm.
Madelyn Helling Library
Community Room



Aperture Fever
by Lonnie Robinson and Tom Osypowski


No one since the time of Galileo, has been more responsible for the spread of Aperture Fever than John Dobson.  He revolutionized Amateur Telescope Making by pioneering the building of large aperture telescopes – light buckets.  

Aperture is the diameter of the first optical component (mirror or lens) of a telescope which determines how faint and the details which can be seen.  Often after a first scope Aperture Fever begins and then the question is what will the cure cost?  The talk will explore the tradeoffs from building your own to purchasing a truly large instrument with all the bells and whistles.

Bring a friend ... bring the kids!

President’s Rant

Hello Astro-friends,

I am ready for some warmer weather. I will enjoy getting out to look at the sky with a few friends so that we can polish our observation skills. I don’t know about yours, but mine are certainly rusty.

We began our 11th year with a good presentation by Barry Mingst and had another wide-ranging discussion at Astronomy on Tap in March.

This meeting on April 4th will also be interesting with a presentation by Tom Osypowski and Lonnie Robinson.

RIP Stephen Hawking, you gave the world much to consider.

Will NASA ever get the James Webb Telescope launched? I don’t want them to put it up just to fail, but every time that it gets within a year to launch, they seem to push it back another year or two. I understand all the excuses, but maybe they shouldn’t give a date, just give us progress reports and work-remaining reports. Just sayin’.

Finally, check out Dave Buchla’s column for upcoming events. We can always use help. And watch for the next Astronomy on Tap.

See you all at the meeting.

Clear skies,


Outreach - David Buchla 

We had a successful Science Night at Scotten School with lots of enthusiastic kids. My thanks to our awesome volunteers. Paul Bacon, Greg Dolkas, Stormy Nelson, Byron Ross, Dan and Betsy St. John worked hard in setup, Stormy helped lots of kids make Star Wheels and Paul had an inside display of a computer-controlled scope. Nate Anderson helped with take down.  Greg and Byron set up scopes outside and excited kids got to see the moon. (It was too early and bright for anything else.) I was surprised that it cleared enough to have decent viewing – two hours before it had been raining. We had several of the displays from previous Astronomy Days including always popular “Hands-on-Science”.

Our next activity is the STEAM expo (Science-Technology-Engineering-Arts-Math) at the Nevada County Fairgrounds on Saturday, April 7 from 9 am to 3 pm. I’ll be there with materials at 8 am for setup. We will have much the same materials as at Scotten School including Star Wheels, displays, “Hands-on-Science”, and we could use a demo scope inside if anyone wants to bring one. STEAM is put on by the Nevada County Schools office and attracts lots of visitors, so we will be busy. (Last year there were 1500 visitors!) All help is much appreciated – even if you can help a couple of hours, it will be appreciated.



Astronomy on Tap

NC Astronomer members continue to enjoy the beer  and 'blather' at the Ol' Republic Brewery.  Their beer selection is quite comprehensive and they seem to enjoy naming beers after astronomical topics. 

Our discussions in April will begin with the topic 

"Rapid star death during a Super Nova Star"

  This NASA animation depicts a rare supernova type known as a fast-evolving luminous transient, or FELT. NASA's Kepler space telescope has found such an object.

To prepare for this discussion, please follow this link and

review the super nova process: FELT (Fast-Evolving Luminous Transients).

Wednesday, April 18th at 5pm

We will also continue our discussion on Conic Sections and

review the NASA projects: JWST & WFIRST

[James Webb Space Telescope and the Wide-Field Infrared Survey Telescope ]

Ol' Republic Brewery!


Secretary/Treasurer - Paul Bacon


Our Mission is:

'Bringing' Astronomy to the Public'

a BIG Thank You

to all our members who join and make our programs possible!

I will be collecting 2018 membership contributions

($20/year for member or family)

at our meeting on April 4th,

If you can't make the meeting, send your check to:

          NC Astronomers, %Paul Bacon,                    
10572 Oak St., Grass Valley, CA 95945


This article is provided by NASA Space Place.
Visit to explore space and Earth science!                                                 

Measuring the Movement of Water on Earth

By Teagan Wall

As far as we know, water is essential for every form of life. It’s a simple molecule, and we know a lot about it. Water has two hydrogen atoms and one oxygen atom. It boils at 212° Fahrenheit (100° Celsius) and freezes at 32° Fahrenheit (0° Celsius). The Earth’s surface is more than 70 percent covered in water.

On our planet, we find water at every stage: liquid, solid (ice), and gas (steam and vapor). Our bodies are mostly water. We use it to drink, bathe, clean, grow crops, make energy, and more. With everything it does, measuring where the water on Earth is, and how it moves, is no easy task.

The world’s oceans, lakes, rivers and streams are water. However, there’s also water frozen in the ice caps, glaciers, and icebergs. There’s water held in the tiny spaces between rocks and soils deep underground. With so much water all over the planet—including some of it hidden where we can’t see—NASA scientists have to get creative to study it all. One way that NASA will measure where all that water is and how it moves, is by launching a set of spacecraft this spring called GRACE-FO.

GRACE-FO stands for the “Gravity Recovery and Climate Experiment Follow-on.” “Follow-on” means it’s the second satellite mission like this—a follow-up to the original GRACE mission. GRACE-FO will use two satellites. One satellite will be about 137 miles (220 km) behind the other as they orbit the Earth. As the satellites move, the gravity of the Earth will pull on them.

Gravity isn’t the same everywhere on Earth. Areas with more mass—like big mountains—have a stronger gravitational pull than areas with less mass. When the GRACE-FO satellites fly towards an area with stronger gravitational pull, the first satellite will be pulled a little faster. When the second GRACE-FO satellite reaches the stronger gravity area, it will be pulled faster, and catch up. 

Scientists combine this distance between the two satellites with lots of other information to create a map of Earth’s gravity field each month. The changes in that map will tell them how land and water move on our planet. For example, a melting glacier will have less water, and so less mass, as it melts. Less mass means less gravitational pull, so the GRACE-FO satellites will have less distance between them. That data can be used to help scientists figure out if the glacier is melting.

GRACE-FO will also be able to look at how Earth’s overall weather changes from year to year. For example, the satellite can monitor certain regions to help us figure out how severe a drought is. These satellites will help us keep track of one of the most important things to all life on this planet: water.

You can learn more about our planet’s most important molecule here:


An artist's rendering of the twin GRACE-FO spacecraft in orbit around Earth. Credit: NASA

Click to Contact
President John Griffin
Vice President Rick Bernard
Secretary/Treasurer Paul Bacon
Outreach Coordinator David Buchla
At Large Greg Ouligian
At Large Dan St. John

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First Wednesday Of The Month
Madelyn Helling Library
Community Room
980 Helling Way
Nevada City 95959

10572 Oak St.
Grass Valley, CA 95945

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