Saturn’s north pole features a hexagon shaped pattern in the clouds driven by fast winds that wrap the planet. The hexagon is about as wide as 2 Earths. This image taken by Cassini on 2 Apr 2014 is in greyscale.
On 26 Apr 2017, Cassini passed over this same hexagon region but at a much lower altitude. This pass was the first of 22 during the coming months in the Grand Finale of the mission. It will enter the cloud tops 15 Sep 2017 to end the 20 year mission at Saturn. As Cassini made this recent close pass, it imaged the hexagon in greyscale 3 time with filters of red, green, and blue.
Using Photoshop, I combined these RGB greyscale images into one with color. The colors are not necessarily what the eye would see. They are my choices in order to enhance differences in regions and appearance. The large blue object at the bottom is like the eye of a hurricane on Earth, but much larger.
The hexagon pattern can be produced in a laboratory evidenced in this post.
Launched 15 October 1997, the Cassini Mission is in its 20th year. It reached Saturn and entered orbit on 1 July 2004. Details of the mission can be read at this Wikipedia summary. This post is mostly about the maneuvers by Cassini to change its orbit and make 22 close encounters with Saturn in what is called the Grand Finale. End of mission is scheduled for 15 Sep 2017 when the spacecraft plunges into the atmosphere of Saturn ending a long and brilliant exploration of the famous ringed planet, its rings, and 62 moons.
Clean Room Workers Ready Spacecraft | NASA | 1996
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So many stories today about the new Earth-like planets found around a Jupiter sized star. It is hard to keep up and make sense of the new information. This NASA news conference explains the importance and why scientists are so excited.
I will be away from the computer this evening. Comments are welcome but my responses will be delayed.
🔭 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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Fellow blogger and sky enthusiast, Scott Levine, pointed out the grouping of two planets and a star in the southern sky in recent nights. Our overcast conditions finally parted and gave us a beautiful view of the grouping the evening of 13 August 2016.
It was about 9 pm local time as we headed home from a gathering of about 30 friends. We have all been to Cuba in the past 3 years and were celebrating with some Cuban foods and drinks. We looked to the south and saw this view exactly as Scott described it. That is the roofline of our house at the bottom right.
Click to embiggen
Below is a screen shot of the same part of the sky taken from the software Stellarium. Each planet and some stars are labeled. Since Mars and Saturn are in orbits around the Sun, their positions in the sky change each night. Their arrangement with Antares looks different each night. Watch their progress.
The annual meteor shower called the Perseids is due to peak in the early morning hours of August 12. The best show is forecast to occur between 3 am and 5 am on the 12th when the radiant is highest in the northeast. The Moon will have set earlier providing the dark sky essential for their easiest viewing. If the predictions are correct, a rate up to 200 meteors per hour is possible, twice the usual rate. Time exposures over several hours could yield an image like this one from 2009 when the Perseids last gave such a high rate.
NASA | JPL | 2009
The Perseids are dust grains from comet Swift-Tuttle which orbits the Sun every 133 years. Every time the comet orbits the Sun, it leaves more particles. Earth crosses the path of debris each year. Some enter the atmosphere at very high speeds up to 132,000 mph (59 km/s) and burn up in flashes of light. Their Perseid name is because they appear to radiate out of the upper part of the constellation Perseus close to Cassiopeia in the upper right part of this graphic.
The NASA Jet Propulsion Laboratory shared this video summary of the Perseids and some other features of the night sky in August you might find interesting.
What is the best way to view the Perseids? This short video sums up the task. It is very easy. Basically, you need to lie on your back and watch the sky. Thanks to the folks at the Meteoroid Environment Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Their job is to monitor meteor impact hazards to spacecraft.
What if clouds are a problem? A live broadcast of the Perseid meteor shower will be available via Ustream overnight on Aug. 11-12 and Aug. 12-13, beginning at 10 p.m. EDT.
Top findings by scientists with the New Horizons Pluto Mission were published in March 2016 in the journal Science. A list of the highlights is available in this news release from NASA. I will attempt to summarize each finding and their significance.
Images used in this post are from Johns Hopkins Applied Physics Laboratory. Click on any for a much larger and impressively detailed view. Their entire collection of released images is available here for your browsing pleasure. I encourage you to look through the images. Our views of Pluto went from a tiny mottled orb a year ago to ones with great detail and mystery. Each of the 120+ images includes an explanation of the important details.
Now on to the top findings…
1. Geologically active
The ages of solar system bodies can be estimated by counting the number of craters. This method tells us Pluto is about 4 billion years old, a little younger than Earth. The heart-shaped light colored, icy region called Sputnik Planum is devoid of cratering. That indicates it is young no more than 10 million years. Sputnik Planum is smooth and about the size of Texas.
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