his beautiful image from the Cassini spacecraft showing three of Saturn’s moons as crescents is too good to pass up.
The largest moon in the image is Titan (also Saturn’s largest moon), notice how the crescent seems to wrap much around the moon more than the other two. Titan has an atmosphere that refracts light around the moon than it would otherwise would.
Rhea is in the upper left shows more cratering, especially if you click the image to see a larger version. I believe we may be able to see the Tirawa impact basin in the image.
Mimas is the bottom moon in the image. Of the three Mimas is probably my favorite. It has a HUGE impact crater called Herschel – almost a full third of the moons diameter!
Physical charachterisitics and images
for each of the moons can be found at the links to each below.
Spacecraft to moon distances:
To Titan – 2 million km / 1.2 million miles
To Rhea – 3.5 million km / 2.2 million miles (see the Tirawa impact basin)
To Mimas – 3.1 million km / 1.9 million miles (check out Herschel)
Image Credit: NASA/JPL-Caltech/Space Science Institute
The Solar Dynamics Observatory gives us this great view of a coronal mass ejection (CME) from the side of the Sun. The image is captured in the 304 Angstrom Wavelength of extreme ultraviolet light on 17 to 18 June 2015.
Had this CME been directed towards Earth there could have been impacts like those we always hear about, namely communication and power disruptions. The news media usually likes to tell us how bad things could be and sometimes we ignore what they say because, well, they always say it. The truth is all of that stuff could happen and be as bad as they like to say OR anywhere along a continuum between just a beautiful aurora and that doom and gloom scenario.
Being a ham radio operator I can tell you communications disruptions are not really uncommon in such events, they can be kind of fun too. Commercial communication problems would not be fun and we have been on the LUCKY side of things so far.
Anyway, enough rambling; there is a great video of this CME, a four hour period is represented.
Take your pick of videos, they are the same just different formats. (Links to the SDO site):
CME304_June_sm.mov – mov
CME304_June_sm.mp4 – mp4
This morning the planet Mercury is at maximum western elongation. This means we will be able to see Mercury in the early morning just before sunrise especially for the next few days.
Yes, western elongation means Mercury will be in the eastern sky before sunrise. It can be a little confusing at first. The western/eastern elongation is the position relative to the Sun not the Earth.
So western elongation means Mercury is west of the sun and that being true will rise in our eastern sky before the sun. Mercury this morning will reach an altitude of 22 degrees before sunrise. If you have a good view of the eastern sky you will get to see it (for the next few days at least) in the twilight before the Sun gets too bright. I know, it’s early morning for the northern hemisphere but so worth it. I am pretty close to a mountain range and that interferes so I’m taking a drive to get a better look IF the clouds stay away.
In September the planet will reach eastern elongation so it will appear in the western sky just after sunset.
Check it out if you can.
NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Yesterday was the anniversary of the discovery of Pluto’s moon Charon. The moon was found by astronomer James Christy while using the 1.55 meter telescope at the US Naval Observatory Flagstaff Station on 22 June 1978 and announced to the world on 07 July 1978 by the IAU.
Above is the image the moon was spotted in. The image above is Pluto, the image on the left shows a “bulge” near the top that is not in the iamge on the right. The so-called bulge would appear and disappear over time and the period between subsequent “bulges” corresponded to the rotational period of Pluto.
It also turns out this “bulge” was seen and confirmed in hindsight on photographic plates going back to 29 April 1965.
Just think in a few short weeks we will be treated to a very good look at this moon. Quite a difference between then and now already and we haven’t seen anything yet!
Image: USNO / NASA