Posts Tagged ‘JPL’

04/25/2017 – Ephemeris – The Cassini spacecraft is on its last 22 orbits of Saturn

April 25, 2017 2 comments

Ephemeris for Tuesday, April 25th.  The Sun rises at 6:41.  It’ll be up for 13 hours and 58 minutes, setting at 8:40.  The Moon, 1 day before new, will rise at 7:08 tomorrow morning.

In the early hours of last Saturday, Earth Day, The Cassini spacecraft, orbiting Saturn for the last nearly 13 years, made its last pass of Saturn’s giant moon Titan.  Over the past 13 years Cassini has been using Titan as a kind of fulcrum to leverage its orbits of Saturn, returning time and time again to both study this strange moon and to propel it via gravity assists into a myriad of orbits.  This time however, with one last gravitational assist, Cassini was flung into a series of 22 daring orbits which will take it into a couple of thousand mile gap between the rings and the planet.  On orbit 22, if it doesn’t collide with an errant ring particle, Cassini will burn up in Saturn’s atmosphere, going something like 70,000 miles an hour on September 15th.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.


Cassini's grand finale

In its planned last 22 orbits of Saturn, the Cassini spacecraft will pass between the innermost ring and the planet itself. Credit NASA, JPL.

04/24/2015 – Ephemeris – The Dawn spacecraft is descending to dwarf planet Ceres’ day side

April 24, 2015 Comments off

Ephemeris for Arbor Day, Friday, April 24th.  Today the Sun will be up for 13 hours and 54 minutes, setting at 8:38.   The Moon, 1 day before first quarter, will set at 2:26 tomorrow morning.  Tomorrow the Sun will rise at 6:42.

The Dawn spacecraft with its ion engine is descending into orbit of that other dwarf planet Ceres, the largest body in the asteroid belt.  Over the past month Dawn has been maneuvering over Ceres’ night side to descend into a polar orbit to better survey the planet.   Last week the Jet Propulsion Laboratory team that has been operating the spacecraft released a video of several photographs of Ceres’ pole as it rotated.  It was still a crescent view, but soon we’ll see Ceres up close and very personal.  We’ll get a closer look at those enigmatic white spots.  Are they just white ice patches on the surface, or are they ice cryovolcanoes spewing water, or something else?  Stay tuned.

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.


Ceres amimation

Ceres animation from April 14-15, 2015. Dawn was 14,000 miles (22,000 km) from Ceres. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.  Click the image to enlarge.

This is a newer animation than the one mentioned in the transcript above that was actually written on the 19th.  Here’s a link to the NASA page that describes the image.  It also has a link to an enlarged frame containing the double bright spot.

Processed image

This is a processed still image of Ceres from the above animated sequence of images.

There’s no help figuring out what they are but the smaller spot is resolved into two spots.  The bright one is still unresolved.  As of yesterday the Dawn spacecraft should be in its first circular orbit of Ceres at an altitude of  8,400 miles (13,500 km) from Ceres for a few weeks before descending to a lower orbit of Ceres the starting the first week in May.


01/16/2014 – Ephemeris – NASA/JPL Solar System Ambassador

January 16, 2014 1 comment

Ephemeris for Thursday, January 16th.  The sun will rise at 8:15.  It’ll be up for 9 hours and 14 minutes, setting at 5:29.   The moon, 1 day past full, will rise at 6:25 this evening.

I am proud to announce that I have been appointed  one of the NASA Jet Propulsion Laboratory’s new 38 new Solar System Ambassadors for 2014.  Solar System Ambassadors are volunteers that host star parties, and provide presentations about space, the universe, and NASA missions to promote awareness of the STEM or Science, Technology, Engineering and Math fields as career choices or at least to encourage the students to become more science literate voters.  Ambassadors work with school classes, scout groups and non-profit organizations.  Being now newly retired I have the freedom of daytime visits.  I will be serving the northwestern Lower Peninsula of Michigan.  Interested?  The easiest way to initially contact me by email is at or

Times are for the Traverse City/Interlochen area of Michigan.  They may be different for your location.