During 2017, the inner solar system has been joined by several comets. Most are not bright enough for the casual observer to see. Those with dark skies and large enough telescopes have enjoyed one of these visitors, comet C/2015 V2 (Johnson). The discovery was by Jess Johnson in late November of 2015.
Comet naming is systematic. The letter C means it is a one time visitor. A letter P would be used if the comet returned periodically such as Halley. Discoveries are denoted by the half-month in which they occur. The first comet found in the first half of January would have A1 at the end of the label. If another was found in the first half of January it would be A2, etc. The fourth one found in the second half of February would be labeled with D4. The V2 for Comet Johnson means it was the second comet discovered in the second half of November. The eleventh month means the 21st and 22nd letters of the alphabet (U and V) are used for those half-months.
One of the better images of C/2015 V2 is from Tenagra Observatories in Arizona. Details of their observation is at this link. Click to embiggen.
I was curious what the orbit looked like. I found a web site by Dominic Ford called In-The-Sky. His simulation showed the orbits of the inner planets and the comet which could be rotated and viewed from different perspectives. Here is a short screen video capture from his site. The video shows the comet on 30 May 2017.
I requested an image of Comet Johnson from the University of Iowa Gemini robotic telescope in Sonoita, Arizona. It was taken at 12:42 am CDT the morning of 30 May. The 60 sec exposure in visible light showed the halo and faint tail. Click to embiggen.
Some things we keep over the years carry strong ties and meaning in our lives. In our house, we try to not keep very many things, only the most important. Given the chance, we part with some of the things we’ve kept that might not have much meaning any more. When we die, we don’t want to leave the job of sorting through our stuff to our children.
I sorted some books on the shelves to see which could be donated to the public library for their sale. I decided to keep this one. The book and I have connections that goes back several decades. I will explain.
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Zooniverse is a citizen science network. Hundreds of thousands of volunteers worldwide who take part in science projects online. I participate in several and wrote about Zooniverse in a previous post. Researchers invite volunteers to take part in many types of projects from astronomy to zoology.
Recent hurricanes in the Caribbean islands caused much loss of life and damage to property and ecosystems. Zooniverse volunteers were asked to help relief efforts by examining satellite images of the islands before and after the hurricanes. By comparing before-after images of the same places, structural damages, flooding, road blockage, and temporary housing were assessed. Color coded maps were made from the assessments showing the places most in need of relief efforts. Rapid response was extremely important. Here is an example of one of those ‘heat maps’ of the island of St. Thomas. Red and purple show the greatest need for help.
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Sunrise today was 7:23 am. At 6:49 am, the Moon was barely above the eastern horizon, presenting a narrow sliver of reflected light. Earthshine lit the rest of the Moon faintly.
A wider view showed the star Porrima, goddess of prophecy, watching the proceedings nearby.
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There are only four known types of force found in nature: Gravity, Electromagnetic, Strong Nuclear, and Weak Nuclear. Each has particular characteristics. This table lists them from weakest to strongest. The last column shows if the carrier of the force was observed by experiment and verified.
Lederman Science Education Center | Fermilab
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Bright Venus and Mars in center at 6:45 am today. They are joined by Sigma Leo at top and Tau Leo lower right.
Simulation of the passing of Mars by Venus between 2 October and 8 October.
Two days earlier I posted some photos of Venus and Mars in the pre-dawn light. The positions of Venus and Mars were getting closer each morning. October 5th was to be the day they would be closest at 1/4˚ apart. For comparison, the Moon’s diameter is only 1/2˚ wide.
Our weather forecast said it would be raining on the morning of the 5th. I assumed that previous post was going to be all I would get to share about their conjunction. Today I looked outside before 6 am and was thrilled to see a clear sky. I got the camera and tripod to capture the unexpected scene.
First is a screen capture from my planetarium software showing the planets on the 3rd and the 5th of October.
Next is my photograph of Venus and Mars at 6 am on the 3rd of October. It is adjusted to be the same scale as the first image.
Finally, my photograph of the two at 6 am on the 5th of October. It is adjusted to be the same scale as the first image. They were about half the width of a full moon apart. Mars was hard to see without the aid of binoculars. By 6:30 am, the sky was too bright to see Mars. Venus remained bright and easily seen. In fact, in clear skies, Venus is not hard to see in the daytime if you know where to look.