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Archive for the ‘Dwarf Planet’ Category

11/05/2019 – Ephemeris – Is the asteroid Hygiea the smallest dwarf planet?

November 5, 2019 Comments off

Ephemeris for Election Day in some places, Tuesday, November 5th. Today the Sun will be up for 10 hours even, setting at 5:26, and it will rise tomorrow at 7:27. The Moon, 1 day past first quarter, will set at 1:12 tomorrow morning.

The asteroid Hygiea is the 4th largest asteroid in the asteroid belt between Mars and Jupiter. After much study with the European Southern Observatory’s Very Large Telescope (VLT) it appears that Hygiea is very nearly spherical. Only the largest asteroid and dwarf planet Ceres is more spherical, and it’s over twice as large. Ceres is 587 miles (945 km) in diameter. Hygiea is 267 miles (430 km) in diameter. By current definition that a body not fitting the definition of planet because it hadn’t cleared it’d orbit of other objects could have the classification of dwarf planet of it was round, or in astronomer-speak has achieved hydrostatic equilibrium. If the International Astronomical Union agrees it would be the smallest dwarf planet.

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

Addendum

SPHERE image of Hygiea

A new SPHERE/VLT image of Hygiea, which could be the Solar System’s smallest dwarf planet yet. As an object in the main asteroid belt, Hygiea satisfies right away three of the four requirements to be classified as a dwarf planet: it orbits around the Sun, it is not a moon and, unlike a planet, it has not cleared the neighbourhood around its orbit. The final requirement is that it have enough mass that its own gravity pulls it into a roughly spherical shape. This is what VLT observations have now revealed about Hygiea.

For more from Universe Today: https://www.universetoday.com/143897/asteroid-hygiea-is-round-enough-that-it-could-qualify-as-a-dwarf-planet-the-smallest-in-the-solar-system/.

06/18/2015 – Ephemeris – 26 days to Pluto!

June 18, 2015 Comments off

Ephemeris for Thursday, June 18th.  Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31.   The Moon, 2 days past new, will set at 10:57 this evening.  Tomorrow the Sun will rise at 5:56.

I hope everyone’s been following the progress of the New Horizons spacecraft as it nears the Pluto system.  It will reach and pass through the Pluto system on July 14th, only 26 days from now after a journey of 9 years. Now, Pluto is more than a dot in the probe’s cameras, which are used to look for possible hazardous rings of debris, more moons and for navigational purposes.  New Horizons is aimed for a window less than a hundred miles on a side, and a few minutes in time.  All its moves to study Pluto and its moons have been pre-programmed in and actually tested two years ago to make sure everything works.  We will not hear from the spacecraft on encounter day, it will be too busy.

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

Addendum

New Horizons

Artist conception of the New Horizons spacecraft at Pluto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

New Horizon's trajectory

New Horizon’s trajectory through the solar system. Credit: NASA/APL.

Encounter Timeline

New Horizons Encounter Timeline. Credit: NASA/JHAPL.

New Horizons at closest approach to Pluto

New Horizons at closest approach to Pluto. Credit: NASA/JHAPL.

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.

Addendum

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.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

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.

 

04/23/2015 – Ephemeris – New Horizons’ first glimpse of Pluto and Charon in color

April 23, 2015 Comments off

Ephemeris for Thursday, April 23rd.  Today the Sun will be up for 13 hours and 52 minutes, setting at 8:37.   The Moon, 2 days before first quarter, will set at 1:44 tomorrow morning.  Tomorrow the Sun will rise at 6:43.

Last week NASA’s New Horizons team running the spacecraft that’s been in flight to the dwarf planet Pluto released their first color of Pluto and it’s moon Charon.  The photo doesn’t show any surface features.  That’s to come in the next month or two.  However, Pluto shows kind of a pale orange-pink color, hinting of the colorful images to come.  Charon is a dull gray like the dwarf planet Ceres, which Dawn is approaching, and our own Moon.  How could two bodies with a common origin appear so different?  Stay tuned.  New Horizons will pass through the Pluto system in a couple of hours on July 14th, but will send back the mother lode of its data over the next 16 months.

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

Addendum

Pluto and Charon

First color picture of Pluto and its moon Charon taken by the New Horizons spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.  Click to enlarge.

From the NASA website:

“This image of Pluto and its largest moon, Charon, was taken by the Ralph color imager aboard NASA’s New Horizons spacecraft on April 9 and downlinked to Earth the following day. It is the first color image ever made of the Pluto system by a spacecraft on approach. The image is a preliminary reconstruction, which will be refined later by the New Horizons science team. Clearly visible are both Pluto and the Texas-sized Charon. The image was made from a distance of about 71 million miles (115 million kilometers)—roughly the distance from the Sun to Venus. At this distance, neither Pluto nor Charon is well resolved by the color imager, but their distinctly different appearances can be seen. As New Horizons approaches its flyby of Pluto on July 14, it will deliver color images that eventually show surface features as small as a few miles across.”

03/06/2015 – Ephemeris – Learn about this year’s adventures in exploring the soiar system tonight

March 6, 2015 Comments off

Ephemeris for Friday, March 6th.  The Sun will rise at 7:12.  It’ll be up for 11 hours and 24 minutes, setting at 6:36.   The Moon, 1 day past full, will rise at 7:47 this evening.

This evening yours truly will be giving a program at the monthly meeting of the Grand Traverse Astronomical Society at 8 p.m. at Northwestern Michigan College’s Rogers Observatory.  It’s entitled Asteroids and Dwarf Planets and Comets, oh my!  It’s about the three solar system bodies being visited this year by spacecraft from NASA and the European Space Agency.  The asteroid is Ceres, which the Dawn spacecraft entered orbit of today.  The dwarf planet is Pluto which is the target of a summer flyby by the New Horizon spacecraft.  The comet is 67P/Churyumov–Gerasimenko orbited by ESA’s Rosetta spacecraft.  There will be a star party at 9 p.m. following the meeting.

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

Addendum

Oh My!

Apologies to MGM.

Vesta as Dawn headed off to Ceres.

Looking back at Vesta as Dawn headed off to Ceres. Credit: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA

Ceres 2/19/15

The bright spot is two. Picture taken February 19, 2015 from 29,000 miles (46,700 km). Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA.

New Horizons

Artist conception of the New Horizons spacecraft at Pluto. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

July 14th animation

An animation of Comet 67p/Churyumov–Gerasimenko rotation on July 14, 2014. The 30 pixel wide image has been smoothed. The Rotation rate is 1 rotation every 12.4 hours. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA