Our home has many can-light ceiling fixtures. We replaced the original incandescent bulbs with CFL in many of them and noticed some cost savings on our electric bill for several years. More recently we added some LED style.
Bulb costs, duration of use, and total cost of use are some of the quantities tabulated in the chart below from wikipedia. I don’t know how recent are the values. But, they illustrate the cost savings with LED. With LED costs coming down, the savings is improving.
The main problem with an incandescent bulb is that about 75% of the energy needed to operate it is wasted as heat energy to the surroundings. Only about 25% goes toward making light energy. The CFL and LED bulbs convert a much greater fraction of their operating energy into light energy. As a result, they need less electrical energy to produce the same light output as an incandescent.
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One of these images is of the Moon on 2 Feb 2017. The other image is of Venus on 3 Feb. Can you tell which is which? What is your reasoning?
I headed home after attending the public lecture on aurorae by University of Iowa professor Craig Kletzing. One part of his talk included a demo of color emissions from the element oxygen. It is responsible for nearly all the colors associated with aurorae. We needed diffraction grating glasses to see the demo effect such as these.
As I drove home, I noticed the bright crescent Moon. I stopped the car to look through my grating glasses. Once home I set up the camera with the grating over the lens. It was a nice way to end the day.
🔭 Updates an earlier post to include recent changes and information.
As an amateur astronomer, I use desktop planetarium software to plan viewing sessions and keep track of the planets and Moon. There are many products available for all computer platforms and smartphones. A Google search yields links to many sources. I downloaded and use the open source Stellarium on my desktop computer. It can be customized to your location and is free. For Android and Mac phones and tablets, I like SkySafari. It isn’t free.
Online planetarium sites are popular and offer many features. Below are highlights of some I find interesting. Each has multiple features, a unique look and feel, and different levels of detail. They can help satisfy your curiosity about astronomical events.
I limited this post to include only a few select sites and links. Since many are available, it’s easy to be overwhelmed with too much information. I hope these few of top quality will motivate you to investigate the sky and enjoy what it has to offer. I welcome reader questions or reviews about using these tools or others you find helpful.
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On 24 January 2004, NASA’s Mars Exploration Rover Opportunity landed and started exploration. It joined the Spirit Rover which landed three weeks earlier on a different part on the Martian surface. The twin rovers were designed for mission lifetimes of 90 days.
Spirit’s last communication with Earth was 22 March 2010 more than six years into the mission. Opportunity is still operating well and continues to return images and data to Earth after thirteen years. It recently completed a marathon of distance travelled. Detailed maps are available here. To celebrate entering teenage, NASA Jet Propulsion Laboratory released this entertaining video about the milestone.
With morning coffee in hand, this seemed a good way to start my day. What follows is a discussion of the rise of populism as seen by two people from the U.S. and U.K. It provided a lot of insights. I understand better what the term means and how it manifests in the political theaters of Europe and the U.S.
Nick Clegg and Jonathan Haidt appeared at Emmanuel Centre in London on 21 November 2016. The group Intelligence Squared hosted their discussion. They spoke for about 45 minutes and then took questions for another 45 minutes.
This post is a follow-up to one from a week ago. See below the line break for the original.
Thanks to comments by readers, there are three resources to promote which discuss the need for careful, considered dialogue and planning with regard to our nation’s domestic and military nuclear capacity. Readers shoreacres and Jim Wheeler discussed two resources by Thomas Nichols. The third resource is a recent NOVA program about the nuclear option.
First, what if we could rebuild our nuclear weapon forces from scratch? How should it be done?
Second, read the preface and introduction to the Nichols book No Use: Nuclear Weapons and U.S. National Security
Third, the NOVA program Nuclear Option is available for viewing until 8 Feb 2017.
All three urge bi-partisan discussion by all interested parties. One of the reasons hinges on the need for safety and security in our world today. The other reason hinges on the need for a viable solution to the challenges of climate change and global warming.
I believe nuclear energy should play a role in our future. To not examine the ideas and technologies formed in the 50s, 60s, and 70s which brought us to our current position is foolhardy. The world has changed very much since then.
Nuclear Weapons | Do Accidents Happen?
Have there been nuclear weapon accidents or incidents? Yes, there have been many. We are lucky to not have detonations or major spills of radioactive material. An accident near Damascus Arkansas on 18 Sep 1980 illustrates how a simple event can cause a situation of monumental potential for disaster.
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