I like to watch movements of the planets which bring them into close encounters, or conjunctions. Some conjunctions are at a time and position in the sky so images taken over a few days can show their movements. Such was the case June 2019. A big challenge to getting well-timed images is cloud cover. We have had too much of it.
This image is a composite of three evenings of images looking west-northwest at 9:30pm. The camera was on a tripod at the same spot framing two light poles. I cut and pasted the locations of Mercury and Mars from the images taken on June 7 and June 20 onto this image taken on June 11. The dates for each are labeled. Click here or on the image to embiggen in a separate tab.
Note that Mercury, in yellow highlight, moved toward the upper left between June 7 and 11. It moved farther to the upper left by June 20. Mars, in white, moved down to the right between June 7 and 11. It continued down to the right by June 20. I hoped to image the two planets on June 17 or 18 when they appeared very close together, the width of a full moon. But clouds happened.
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🔭 Updates an earlier post to include recent changes and new information. 🔭
Desktop planetarium software helps plan viewing sessions and keep track of the planets and Moon. Many products are available for all computer platforms and smartphones. A Google search yields links to many sources. Open source and free Stellarium is on my desktop computer. It can be customized to your location and has a nice look and feel. For Android and Mac phones and tablets, I like SkySafari. It isn’t free but is inexpensive.
Online planetarium sites are popular and offer many features. Below are highlights of a few I like. With multiple features, a unique look and feel, and different levels of detail, they can help satisfy your curiosity about astronomical events. I welcome reader questions or reviews about using these tools or others you find helpful.
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The minor planet 4 Vesta is the 2nd largest asteroid. Ceres is the largest. In recent weeks it has made a turn in the sky and has been well-positioned for views in the evening sky. I got my first view of Vesta through 15x tripod-mounted binoculars in late July. Chart from Sky & Telescope.
Our skies in Iowa have been cloudy and hazy since then. On 22 August, they were clear and offered good seeing. I set up the binoculars pointing south to try once more to see Vesta and was rewarded. Here is the desktop planetarium (Starry Night 7) view looking south at about 9 pm. Several familiar objects are labeled. Click to embiggen.
I scored a first for me tonight. I set up my 15x binoculars on a tripod and did some star hopping with a map to locate 4 Vesta. Vesta is the second-largest body in the asteroid belt after the dwarf planet Ceres. It is currently directly west of Saturn about halfway to the star Antares. I had no way to photograph it using the binoculars. This screenshot of my astronomy program will have to do.
It has begun. Mars is making the turn from its usual eastward progress across the sky. It will appear to move westward for the next two months. At the end of August it will slowly turn and head eastward again. Why? How can that be?
Mars in retrograde 2018 | Click to embiggen
The answer is simple. Earth orbits closer to the Sun than Mars. We move faster than Mars. We are passing Mars at this time. It is the same perspective as when passing another car. The passed car appears to move backward relative to your faster car.
In addition, Mars grows in size when viewed through telescopes until the end of July. After that, it will decrease in size. If you have access to a telescope, look for Mars in the east after sunset. You’ll need a high power to see any detail. Let’s hope the dust storm settles to reveal those details.
The graphic below from BinTel illustrates the apparent change in diameter given in arc-seconds (“). At the end of July, the Moon will appear about 24″ wide. For reference, the angular diameter of the Sun, or a full moon, is about 1800”, half a degree. That is the width of your little fingernail seen at arm’s length.
BinTel | Andy Casely
🔭 Updates an earlier post to include recent changes and new 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 but is inexpensive.
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 have included only a few select sites and links since so many are available. I welcome reader questions or reviews about using these tools or others you find helpful.
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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.