We started today's class by perusing some images illustrating how different in size stars can be. We tend to think of our Sun as being a typical star. In fact, after watching two short videos that showed the progression in size from asteroids through the main planets to our Sun, and from there to red giants and supergiants and finally hypergiants it becomes clear that the Sun is, in fact, tiny compared to some of the behemoths out there. And yet, they're all stars! We finished class by printing out some images of the better-known larger stars and are in the process of identifying where they are in our night sky.

Gwendolyn has a remarkable memory. She had remembered from last week Wednesday, when Bobby led the spy game, that we were going to outline a constellation on her wall in the invisible ink of the spy pen that everybody got. So we agreed that maybe Cygnus the Swan might be a good constellation for this project. Gwendolyn first drew the pattern of Cygnus on her wall, and then we got black paper from the art room, and she repeated the pattern in white pencil. On top of that, we taped images of Albireo, a stunning blue-orange visual binary star that is the head of the swan, Deneb, one of the brightest stars in the summer sky that is the tail of the swan, and an artist's rendition of Cygnus X-1, a binary star in which one companion is a black hole. In conjunction with this, we also talked about the evolutionary end points of stars of different sizes. More to follow!

Bobby was absent today.

After the post-lunch meeting, all the children were gathered in the dining area and were engaged in a spy game that Bobby had devised himself! It was very intricate, well thought-through, and apparently something he had been working on for a while, as I learned afterwards. It was a great success!! Nevertheless, despite the excitement, Bobby still wanted to work on Solar System stuff (he drew a model on his door in invisible ink) and browsed through Astronomy Picture of the Day.

Following on from our last class together, today Gwendolyn and I looked through my Photographic Atlas of the Stars and discussed the various constellations. Some constellations are more reminiscent of what they're intended to represent, whereas for others one needs a lot of imagination. We chose a constellation - Canis Major - and taped fluorescent stars on the wall in the same pattern. We also taped the names of the stars next to them, and in the process learned that the brightest star in Canis Major is Sirius, and it' salsa the (apparent) brightest star in the northern sky. Gwendolyn also learned that you need Greek, Arabic, and Latin when talking about constellations!

As always, Bobby has so many incisive and to-the-point questions. Today's questions were about asteroids – Bobby knew about the asteroid that is due to swing past Earth on Halloween (beyond the orbit of the Moon, though... we'll be OK!) so we looked a bit at what asteroids are. At the same time we talked about the extinction of the dinosaurs due to an asteroid, and the difference between asteroids, meteors, meteorites, and meteoroids. We concluded class by talking about Hubble's tuning fork classification of galaxies.

Another fun class with Bobby. I thought it might be interesting for him to expand the scale we've been working with to go beyond the Solar System – so we looked at the fact that the Solar System is within our galaxy, and there are many, many other galaxies in the Universe that are very far away. I introduced Bobby to the 'lightyear', a common distance of measure in astronomy.

In today's class we talked some more about the planets, and browsed through online resources to collect a good image of each planet, plus Pluto and the Asteroid Belt and the Sun. Next week we'll print these images out and tape them to Gwendolyn's wall with some facts about each object. We also talked a bit about constellations, and Gwendolyn assigned the names of the stars in the Big Dipper that she had put on her wall with another teacher.

Bobby's curiosity is such a pleasure to witness. And his passion for nebulae is so sweet! In today's class we looked at some more images of nebulae, but we also discussed the structure of galaxies, and talked about what comets are (frozen dirty snowballs that swing around the Sun). Bobby knows a lot about astronomy, and when he doesn't know something he asks such interesting and relevant questions.

In today's class we printed out actual images of the eight planets of the Solar System (plus Pluto) and replaced the place marks on the walls of the Batt School corridor with the images. I also took the opportunity to tell Bobby a little bit more about each planet as we collected the material. To conclude class, we searched the archives of Astronomy Picture of the Day in search of more nebulae.