This upcoming Thursday’s issue will be #900 for this newsletter, which boggles my mind. I can’t believe I’ve put out so many issues; I’m certainly near a million words written, if not more.

Not only that, but July 3^rd is aphelion, when the Earth is most distant from the Sun on its ever-so-slightly elliptical orbit. On top of that, today, June 30, is Asteroid Day, the international day of recognition of the importance of asteroids and the danger they represent to our planet — this is held on the anniversary of the Tunguska impact in Siberia in 1908. 

So I figure, what better confluence of cool astronomy dates to have subscription sale?

Normally, this newsletter is $6/month or $60/year, but for new signups (or renewals) I’m discounting that 20%, so the sale price is $4.80/month or $48/year! 

Premium (aka paid) subscribers get the usual free Monday issue as well as full issues on Tuesdays and Thursdays, complete access to the BAN archive (almost 900 issues strong now!) and can also join the conversation after each issue in the comments section.

If you don’t already have a free or premium subscription, please sign up here. When you enter your email address it’ll take you through the steps to get a subscription, and you’ll see the discounted prices.

If you do have a subscription already, to get the sale price first scroll up to the top of this page. If you see a log in button in the blue banner, click it. Once you’ve done that (or are already logged in) click the avatar icon on the top right. Choose “Manage Subscription” in the dropdown. If you’re a free subscriber you’ll be able to upgrade to Premium there, and again you’ll see the discounted prices when you upgrade.

This discount will be good for one year: if you sign up for a month you can get the discounted rate for the next 11 months after, and if you sign up for a year you get a full year. After that period is up, you can continue the subscription at the regular rate. You can also always unsubscribe at any time by going to that page again, scrolling to the bottom, and clicking “unsubscribe”.

This discount sale will end on July 9 at noon Eastern (US) time. So please sign up!

Right now, this newsletter is a large fraction of my total income, about half. Literally, paying subscribers support me in my ability to write. And not-so-incidentally to do other things like pay my mortgage and bills, eat, and so on. I seriously appreciate the folks who get premium subscriptions, so thank you very, very much!

And now, how about some astronomy?

The Andromeda Galaxy is the nearest big galaxy to our own Milky Way. It’s a near twin of us, too, a big spiral galaxy so close — just 2.5 million light-years, which is right next door on a cosmic scale — that it’s visible to the naked eye from a dark site.

My friends with the Chandra X-Ray Observatory just released a very cool image of our neighbor, combining images from ground- and space-based observatories that detect light across the electromagnetic spectrum:

Whoa! Trippy. Click here for a very large version of it.

This is a combination of images from a bunch of different observatories, including (deep breath) X-rays from the Chandra X-ray Observatory and XMM-Newton (shown in the images as red, green, and blue), ultraviolet from GALEX (blue), visible light from astrophotographers Jakob Sahner and Tarun Kottary (also red/green/blue), infrared data from Spitzer Space Telescope, IRAS, COBE, Planck, and Herschel (red, orange, and purple), and finally radio from the Westerbork Synthesis Radio Telescope (red-orange). (phew). 

I knew of most of these images, having written about them before (especially the UV one from GALEX, since that was part of a meme many years back). But I wasn’t aware Chandra and XMM-Newton had viewed the entire galaxy! They have relatively small fields of view, and Andromeda is huge on the sky, many degrees across. Color me (haha! Ha!) impressed.

The Chandra site has the individual images that make up the composite available, too, if you want to see.

There’s a lot here. The center of the galaxy has a supermassive black hole (at about 150 million times the mass of the Sun, it’s much beefier than our own Sgr A*). It’s eating material, though at a relatively sedate rate, but there’s still enough of a disk piled up around the black hole that it gives off X-rays, so it’s bright in those wavelengths. There are also tons of regular-sized black holes orbiting other stars and gobbling down matter; those emit X-rays and are seen as dots all around the image.

The companion dwarf elliptical galaxy M32 is to the lower right, and to the upper left is a huge arc of material, a cloud of gas that has enough oxygen in it to glow bluish in visible light. It was only discovered recently and its origin is unknown; I wrote about it for Scientific American.

Andromeda starts to become visible in the fall, rising to the northeast for northern hemisphere observers. It’ll be nice to see it again. And when I do I’ll think of this image. It’s one of the most well studied objects in the sky (in fact it was studied by Vera Rubin, which is the “excuse” the folks at Chandra gave for releasing this image, since the telescope named after her just opened its eye for the first time (and come to think of it, my very first science paper was about a supernova in Andromeda)), but, as that weird arc shows us, there’s still a lot more to learn about it.

You can email me at [email protected] (though replies can take a while), and all my social media outlets are gathered together at about.me. Also, if you don’t already, please subscribe to this newsletter! And feel free to tell a friend or nine, too. Thanks!