Asteroid 4 Vesta: Far Away, Closer and Very Close Indeed !

[John]

I've had a lovely session with my Takahashi 100mm refractor tonight. Particularly enjoyable because of the awful weather we seem to have had for the past month - a clear and reasonably dark sky for a decent period seems a real novelty !

I've observed a wide range of targets from Venus at dusk out to galaxies "far, far away". The distant gas giant Uranus, binary stars, star clusters, star formation nebulae, planetary nebulae and super nova remnants have also been visited and admired over the past few hours.

I don't generally observe asteroids that often but tonight one of the largest in the asteroid belt, 4 Vesta, was conveniently positioned in Cetus near the 4th magnitude star Mu Cetus. At magnitude 7.7 4 Vesta was not easy to pick out in the 6x30 optical finder that I was using but the star hop from Mu Cetus was pretty simple so I had no difficulty identifying the star-like point of light amongst a distinct field of background stars. This is the Stellarium view of 4 Vestas position tonight:

And a point of light is all that 4 Vesta appears as in the scope, even at high magnifications. While it is a giant among asteroids, 4 Vesta is a mere 550km or so in diameter and currently a bit over 300,000,000 km from Earth. Stellarium estimates its apparent diameter at .3 of an arc second. I don't know how accurate that is but my 100mm refractor was not going to show its disk, thats for sure !

Despite the modesty of its visual appearance, I was very happy to be observing this little worldlet during its 3.6 year journey around the Sun.

A few years ago NASAs DAWN spacecraft visited 4 Vesa and produced some outstanding imagery such as this example showing the whole asteroid in all its scarred glory. 4 Vesta has clearly been though a lot in it's 4.6 billion year existance:

Now one of my other astro-related interests is meteorites. I currently have a small collection of specimens of the main types built up over the past 12 months or so. Three of my samples are small representatives of a group of meteorites known as HEDs - an abbreviation for Howardite, Eucrite and Diogenite. These are types of achondrite meteorites so were formed through melting and recrystalisation of igneous rocks.

The exciting thing about the HED group of metorites is that we are now fairly certain that they originated from the asteroid 4 Vesta !.

So I thought it would be fun to include some photos of my little specimens of 4 Vesta in this report. Perhaps one day a sample return mission will bring back some material from 4 Vesta so that it can be compared with the meteoric samples that we have ?

Here are some pictures of my specimens of these 3 types. The green cube is 1 cm square for scale - these are small pieces of rock !
Of these 3, only the Tatahouine Meteorite (the greenish one) was actually seen to fall. The other 2 were finds in the north african desert regions. Small fragments of that distant body that I was observing earlier though my telescope. Rather awesome

 

 

 

 

[Marvin Jenkins]

If I have clear skies tonight I am going to get right on this. I find meteorites fascinating. To be holding something that was once flying around in space is incredible. I have always had a dream of owning a decent size nickel iron meteorite with thumb printing. I know they can be bought on the web but I have so much more astronomy kit to get so it will just have to wait.

Marv

[John]

2 hours ago, Marvin Jenkins said:

... I find meteorites fascinating. To be holding something that was once flying around in space is incredible. I have always had a dream of owning a decent size nickel iron meteorite with thumb printing. I know they can be bought on the web but I have so much more astronomy kit to get so it will just have to wait.

 

One of my suppliers is based in France Marv:

http://meteor-center.com/

[jock1958]

Very interesting report @John and to think you have some of the fragments from 4 Vesta. 

Made it out late last night for the first time in ages and made great use of goodies I acquired from Mr Hardie's SGL megga sale. Tried out the TV UHC filter with my 31mm Nagler & 14 mm Delos on M42.....wow!! best I've ever seen it in my fairly LP skies, fantastic contrast with a beautiful green hue.

[Marvin Jenkins]

Nice one John thanks for the link. Very reasonable prices too. Definitely something I will get into in the future.

Thats me with my hand on a very expensive nickel iron lump at Greenwich between Christmas and new year. Older than planet Earth apparently.

[Littleguy80]

Excellent report, John. Nice link back to your meteorite collection. Very neat to have a little bit of Vesta. I’ve had a bit of a fascination with asteroids even since I first saw asteroid Florence’s near pass in 2017. I observed asteroid 5 (Astraea) and asteroid 192 (Nausikaa) last night which brings my total up to 13 asteroids/minor planets observed now. Asteroid 5 is pretty close to the Beehive at the moment and reaches opposition on the 21st. I feel very much inspired to revisit Vesta after reading your report  

[Stu]

Great stuff John, very interesting report and nice link to your collection. Glad you were able to make use of the rare clear sky too.

Just out of pure curiosity, do we know how they know these meteorites are from Vesta?

[Paul73]

Good question Stu. As the proud owner of a couple of little lumps of Vesta, I’ve wondered that as well!

I should really take a few minutes to track down Vesta visually.

Paul

[John]

39 minutes ago, Stu said:

...Just out of pure curiosity, do we know how they know these meteorites are from Vesta?

It was first proposed back in the 1970's that 4 Vesta was a good candidate parent body for the HED group of achondrite meteorites. The asteroid is large enough to have had and maintained a differentiated structure, ie: a crust, mantle and metallic core and also at some point the tectonic activity required to produce achrodrite rocks. Hubble images of 4 Vesta suggested massive impact structures and the events that created them would have liberated a vast quantity of material some of which, over a period of millions of years could have found its way to the Earth. 

NASA's DAWN mission orbited Vesta between 2011 and 2012 collecting masses of data and images about the make up of the asteroid. This data has added weight to the theory about the parent body of the HED meteorites being 4 Vesta. It's not completely proven but it is the strongest candidate I believe.

Some more here on this if you are interested:

https://www.eurekalert.org/pub_releases/2019-06/tiot-uth061119.php

Analysis of the meteorite samples today can show not only what minerals and other substances they contain, when they were formed on their parent world, indicate how long they were in space and also how long they have laid on Earth. Clever stuff

 

 

[cloudsweeper]

Great account John.  I had a look at that 3rd largest asteroid early last month.  Fantastic to now actually see some bits of it!

Doug.

Edited January 17, 2020 by cloudsweeper

[mattjanes100]

Very interesting report, nice to see something a little different!