Thoughts On Asteroids And Protoplanets

Latest photo of Vesta from the Dawn probe, which will begin orbiting the asteroid on July 16. Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

We’re getting closer. The latest image from the Dawn spacecraft taken on June 14 at a distance of 165,000 miles shows a few more details on Vesta, including, dare I suggest, the outline of a crater at upper left.

One rather odd thing about the Dawn website is their description of Vesta. The writers refer to it as a protoplanet, which is confusing at best. I’ll be sticking with asteroid.

Vesta is currently visible in the constellation Capricornus the Sea Goat near the start of dawn. At magnitude 5.8, it's bright enough to easily see in binoculars. Once the moon leaves the sky, I'll provide finder charts. Created with Stellarium

Protoplanets grew to become planets in the early solar system through the process of collision and gravitational attraction with other protoplanets. Once upon a time, Earth was a protoplanet, but it swept enough enough material to become to planet we cherish today.Vesta and the other large rocky bodies that currently reside in the asteroid belt escaped this process and remained unincorporated, freely-orbiting asteroids. While they may have been potential protoplanets long ago, they’re not anymore. Or am I missing something?

A quick sketch of the supernova from last night June 20. The star to the upper left of the galaxy's center is a foreground star in the Milky Way. Use it and the center to help you spot SN 2011 dh.

We got exactly one half-hour of clear skies last night, our first sight of the stars since early last week. I quickly set up my scope for a look at supernova 2011 dh in the Whirlpool Galaxy also known as M51.

Wow! It just keeps getting brighter. At magnitude 12.3, it’s even easy to see in a 6-inch telescope. The stellar explosion is still rising in brightness since its discovery on May 31, taking its sweet time to peak out. Will it grow brighter yet? Of the 388 supernovae reported thus far this year, it’s the brightest of the bunch and a real standout now in the outer spiral arm of the galaxy.

In just a few hours, the European resupply freighter Johannes Kepler will dive into the atmosphere over a remote area of the Pacific Ocean and burn up in a spectacular display. The craft undocked from the International Space Station yesterday carrying 2,600 lbs. of trash.

The Automated Transfer Vehicle, nicknamed Johannes Kepler, returns to Earth in flames starting at 3:24 p.m. CDT today. Credit: NASA

Kepler arrived at the space station with 3,500 lbs. of cargo plus refuelling propellant and oxygen back in February. Now it returns with unneeded refuse which will burn up harmlessly during re-entry. To read more about Kepler, please click HERE.

Interestingly, the craft carries its own “black box” that will record information on temperatures, accelerations and tumble rates as it breaks apart in the atmosphere.

2 Responses

  1. Hello Astro Bob,
    Won’t spaceship Dawn orbiting Vesta for a year cause an orbit change in Vesta? If so, could the new orbit endanger earth with an impact from Vesta?
    You have a great website, I only recently discovered you when looking for info on today’s flyby of 2011MD.
    — Margaret

    1. astrobob

      Hi Margaret — A spaceship is much too small an object to affect Vesta, a 310-mile diameter asteroid, in any significant way. Vesta is the one that will affect the ship, gradually drawing it into its orbital ‘grasp’.

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