I was thinking about Star Wars and the twin suns rising above Tatooine. These would be called binary stars.
What defines a binary star?
A binary star consist of two star. The bigger one being called the primary and the smaller is called the secondary or companion. The two stars then orbit around their common center of mass. If both star were the same mass then they would orbit around a point half way between them. With one having more mass the common center of mass would be closer to that star. A good example in this animated image from Wikipedia. You can see that both the stars are moving and orbit a single point.
How many are there?
They estimate that about 1/3 of the star systems in the Milky Way have 2 or more stars in them.
Are there planets around them?
Kepler 16b is orbiting two stars. The image above the purple dot is Kepler 16b. This type of orbit is called “P-type” or “circumbinary”. The fun bit is that this planet has been given the nickname Tatooine. Unfortunately it has the mass of Saturn so its not exactly habitable. The other type is where the planet orbits only one of the stars. This is called a “S-type”. Gamma Cephei has a planet in an “S-type” orbit around its primary star.
This was our first ever week of homeschooling and I have to say that it was a success. He did his work without complaining. He worked hard and most importantly he enjoyed it. Student Writing Intensive was a success. I am very glad that I spent the money on that.
Some of his math he whizzed through some he got stuck on but a few minutes of explanation fixed most problems. The other was getting him to write out the steps of the problems rather than doing them in his head. One it allowed him to look back and find his mistake. Two it allowed me to see were the problem was so I could explain it. Mostly he was dropping terms in his head.
He is really liking Rosetta Stone Chinese. He has started to try to use the words in conversation. It would help if I spoke a word of Chinese myself.
Places we’re going and people we’re seeing…
We did a Meetup with other homeschoolers for a hike. Great time and I got to meet some local homeschoolers and my son got to meet some kids. I Wish I had remembered my camera.
We also went to a picnic put on by our supporting school. We got to meet our teachers and other families. We signed up for some co-ops and went for a balloon ride. Good day and my son got to play with some kids. That will help with one of his concerns about homeschooling.
My favorite thing this week was…
I found a grinder attachment for my Kitchen Aid mixer in a thrift store. A new one would have cost me $80. This one was $5.
Still reading”Learn to Think Like Leonardo Da Vinci. I am enjoying it but its taking forever for me to get through. I want Philip to read it after I am done with it.
With back to school this week for my daughter I needed some lunches for her. So I made her sausage rolls. Whole wheat so they are somewhat nutritious. I have trouble getting her to eat a balanced meal at lunch. Left to her own she would have crackers.
I like to make my own bread as it is cheaper and I know what is in it. Mine is about 80% whole wheat. I did a post on it a 2 years ago. I have changed things enough that it deserves a new post.
On Monday I went from plan A to plan B and then onto Plan B Take2 for dinner. Sometimes good things come out of problems. Taco Bites Post.
One of the family favorites this week was Spinach Salad with Teriyaki Chicken on top.
I’m grateful for…
My daughter deciding that green leafy things could be edible. She actually ate the spinach salad.
An asteroid is a small body that orbits the sun. The size range from 10m across and up. The upper end isn’t well defined yet. Anything smaller than 10m across is considered to be a meteoroid. The upper end question is where do they go from being an asteroid to being dwarf planets.
When was the first one discovered? What is the largest asteroid?
The first asteroid to be discovered was Ceres in 1801. It is also the biggest with a diameter a 952km. When it was discovered they considered it to be a planet. As they found more and more of them they stopped calling them planets and renamed them asteroids. In 2006 scientist need to define what a planet is. In doing so they created a category called dwarf planet. Ceres meets the criteria for dwarf planet and is the only one in the inner solar system. It is also still considered to be the largest asteroid.
Where are they located?
Most asteroids are found in the asteroid belt between Mars and Jupiter. Some are found in Trojan points of a planet with Jupiter having the most. Trojan points are 60 degree in front of or trailing the planet. Thus these asteroids travel around the sun with their planet but are not orbiting the planet. The third type and the ones we want to keep an eye on are called Near Earth Asteroids. These have orbits that pass close to Earth.
How many are there?
Millions. They estimate that the belt has between 1.1 and 1.9 million asteroid over 1km in diameter. There are less Near Earth asteroid, about 7000 and only 500 to 1000 of those are over 1 km. Most of the Trojan asteroid are travelling with Jupiter. We think there are a lot of them and maybe as many as the asteroid belt. It is an area we don’t know a lot about yet.
What are they made of?
Another area that we don’t know a lot about. Various forms of rocks for most although Ceres is thought to have an icy crust. Some may be a solid single rock. A lot seem to be rubble piles of smaller rocks held together by gravity.
How do we find them?
The first ones were found by people looking through telescopes and keeping very detailed records. Things that moved compared to the background stars were planets and as stated earlier Ceres. They found a number this way. Later people used photographs and digital cameras through telescopes. A computer can watch an area of space and compare multiple photos for things moving.