Jason Nishiyama @evilscientistca@octodon.social

Want to work out the magnification of a telescope? Well you need to know what eyepiece it is using as changing the eyepiece changes the magnification. Mag=focal length of telescope / focal length of eyepiece. So a 10mm eyepiece on a 1500mm f/l telescope is 150x.

Spectra can be either bright line or dark line. The lines are caused by different elements in the object. Bright lines are from hot or excited gases. Dark from cool gasses in front of a hot object. The lines are in the same position in both for the same elements.

@Canageek got it.

@craigmaloney He's left. Now the adults can talk...

Change your wavelength, change your view. A map of the sky at 800MHz (~37cm wavelength). This is mostly continuum radiation. Done with the 2m dish that we re-mounted today.

2m dish at the observatory finally re-mounted.

@amphetamine Though I think that was Apollo 12.

The red dot marks the Apollo 11 landing site, the first place humanity has set foot on another world.

Galaxies tend to be found in clusters. This one is Abell 2666. The second images show the 11 galaxies visible.

@RefurioAnachro @mewnirebel
Yes. 20cm f3.9 Newtonian with 2.5x barlow. RGB image.

@mewnirebel that was one of the suggestions but was rejected.

The planet Uranus was originally called Georgium Sidus (George's Star) by its discoverer William Herschel. This didn't go well outside of Britain so it was named after the Greek deity of the sky. English speaking astronomers have had to deal with the giggling ever since.

M57 - the Ring Nebula - is a planetary nebula in the constellation Lyra. A dying star that has ejected its outer layers, kinematic studies of M57 suggest that it is actually barrel shaped and that we are looking down one end.

Henrietta Swan Leavitt discovered the Cepheid variable period-luminosity relationship. This relationship links the absolute brightness of a Cepheid type variable star to its pulsation period. This gave us an important standard candle to measure distances across space.

Squeeee!

In the 1920s Edwin Hubble used his discovery of Cepheid variable stars in both M31 and M33 to work out the distance to these two galaxies. This showed that the then called "spiral nebulae" were actually galaxies outside of our own - making our universe much larger.

Seeing is caused by the moving of our atmosphere. It causes stars to twinkle and causes images to be blurry. It can be seen in this movie of Saturn. Good seeing has less motion. Hubble avoids this problem by being in space.

M51 is an interacting galaxy in Canes Venatici. It is located just off the furthest handle star in the Big Dipper. It is about 24 Mly away.

Most of the things on Charles Messier's eponymous list look fuzzy through a small telescope and hence could be mistaken for a comet, which Messier was trying to find. So M40, the only double star on the list, is a bit of a puzzle as to why he added it.