On January 4, 2012, I posted my first BAFact: a short astronomy fact that was brief enough to put on Twitter but informative enough to be interesting. I posted the first one on perihelion the point in Earths orbit when its closest to the Sun and the last one will be a year later.

Because 2012 is a leap year with 366 days, July 5th was the 184th day: the first day of the second half of the year. That means Im more than halfway done!* Appropriately enough, heres the July 5 BAFact:

I post the BAFacts on Twitter, Google+ (where I can flesh them out a bit more and add pictures since theres no character limit), and have a complete archive of them on the blog as well. With 180+ already in the bag, reading those should keep you busy for a while!

I generally link them to previous blog posts dealing with the topic in question, but not always. Ive actually been surprised at how difficult it can be to reduce a topic to 100 or so characters (leaving room for the leading “#BAFact: ” and shortened link, plus room for retweets), and how that limits some topics. I have also been surprised to find out I havent written about some topics! For example, I was thinking recently of making a BAFact about the nearest known black hole, Cygnus X-1, and discovered I had literally never even mentioned it in a blog post! Thats weird but by coincidence that got fixed just this last weekend.

So this exercise in brevity has given me new things to write about. Ill note that there have been arguments over the accuracy of some of the BAFacts, too. Sometimes thats just due to having to be so brief that the description might be misleading if you dont click the link; I struggle with those but usually make them as clear as possible, and hope people actually read the post to clarify. And once I really did just make a mistake; as I recently mentioned I didnt know that recent research had found that zodiacal light is mostly from comet dust and not asteroid collisions, and had to post an immediate correction! But thats OK; I love learning new things, too.

So as we enter the second half of these, I hope you keep up with them and enjoy them. And if you have a beef with them, find a mistake, have something to add, or know of a good picture or story relating to them, follow it up with a tweet of your own! The whole point here is to have fun and learn things. Which, when it comes to science, are exactly the same.

* Well, kinda. Perihelion is actually on January 2, 2013, roughly a day earlier than usual because we have an extra calendar day this year. The Earth orbits the Sun not caring at all for our calendrical contrivances, so when the time comes Ill decide whether to post the last BAFact based on the Earths orbit our roughly-hewn measurement of it.

Here is the original post: