Prograde Vector

From left to right, there's Rhea and Dione, two somewhat unremarkable icy moons, Enceladus, whose fractured crust hides a warm salty water ocean underneath, the famous two-toned moon Iapteus high above, tiny Mimas just near the rings, and distant Titan, shrouded in haze hiding methane seas.

Had a much better imaging opportunity for the infamous interstellar comet 3I/ATLAS the other night and assembled this color composite. Just two minutes per channel, to avoid significant trailing.

Finally, conditions are right to see interstellar comet 3I/ATLAS from my location. Here is a small GIF taken in the brief moments between when it emerged from behind the treetops and when the dawnlight became too overwhelming for my sensor. In just those 4 minutes, its rapid motion is readily apparent. As is the fuzzy coma made from outgassing icy material from its ancient surface.

And now for some more science, also from last night. This is a plot of brightness for the Delta Scuti variable star SZ Lyncis. These regular dips and peaks are a result of the star physically expanding and contracting in cycles of rhythmic pulsation, driven by changes in opacity in its chromosphere!

Another example of some of the amateur astronomy I've been up to recently. This is the red dwarf EV Lacertae. It's a very young star at just 300 million years old, and also one of the closer stars to the Sun sitting at a distance of 16.5 lightyears. EV Lac is known as a flare star, a class of stars which have extreme and unpredictable surges in brightness that last several minutes. This kind of flare activity is quite common among red dwarfs, especially ones as young as EV Lac. Our best understanding of why this is has to do with the fact that young stars rotate quickly. This rapid rotation drives an immensely strong magnetic field. As in the Sun, it is the reconnection of field lines that is thought to drive these flares. But in the case of stars like EV Lac, the field strength is such that the flares produces can dwarf those of the Sun by orders of magnitude. Indeed, EV Lac has been known to produce flares tens of thousands of times brighter than the brightest solar flare on record. All this from a star a third the size of the Sun.

It might seem silly to suggest that you can see a planet many hundreds of lightyears away orbiting another star from your own house with off-the-shelf equipment, but amateur astronomers like myself have been doing it for over a decade! How? Using the same method professionals do - specifically the transit method. Modern commercial CCD and CMOS cameras are sensitive enough to detect the minuscule change in brightness as an exoplanet passes between its parent star and us. And it is a tiny drop in brightness, between 10 and 20 parts per thousand for the largest of planets.

It's these large, close-in planets that are accessible to amateur astronomers, thanks to the relatively deep transits and fast orbits that are easily detectable and can be fully captured in a single night of imaging. This is one of my most recent observations of such a transit. The planet in question is TrES-1b, a world a little larger than Jupiter in a scorchingly-tight orbit that lasts just 3 days. Such planets are called hot Jupiters for obvious reasons. They are large, low-density volatile-rich worlds whose proximity to their star heats their atmospheres to many hundreds to thousands of degrees. In the case of TrES-1b, the average temperature was directly measured with the Spitzer infrared space telescope to be Over 786 °C.

This is perhaps the top contender for my favorite photo I've taken so far. The Triangulum Galaxy the third-largest galaxy in the Local Group, the first being Andromeda and the second being our own Milky Way. It's also the second-closest major galaxy (excluding our own satellite galaxies), sitting at around 2.7 million light-years. Curiously, Triangulum lacks an obvious nuclear bulge, and its core also does not appear to harbor a supermassive black hole like other large galaxies. Instead, models suggest an intermediate-mass black hole of around 1500 solar masses lurks within the nucleus. If this is indeed the case, the reason for such a relatively low-mass central black hole is unknown.

Of particular note in this galaxy are the large H-II emission regions. There are two that are most prominent in this photo, the first being near the bottom right-hand region. This is NGC 604, which is not only the largest star-forming region in Triangulum but also one of the largest known anywhere. It spans over 1500 light-years, dwarfing the famous Orion nebular complex in our own galaxy. The other, located just a little bit leftward from the core, is NGC 595, which is also quite vast at around 440 light-years across.