Notices by Jason Nishiyama (evilscientistca@octodon.social), page 2

Though 1000s of km wide, Saturn's rings are paper thin and only a few tens of metres thick. (NASA Cassini image)

M97 is a planetary nebula in Ursa Major. It is located near the lower pointer star Merak. As a planetary nebula it is the last phase of death of a intermediate to low mass (7 to 1 solar mass) star before the star becomes a white dwarf. #astrophoto

The spikes you see on stars in some astronomical images are diffraction spikes caused by the supports that hold the secondary mirror.

At a little over 2 million light years away, M31 - the Andromeda Galaxy, is the closest large galaxy that looks kind of like our own Galaxy. It and our Galaxy will collide in about 4.5-5 billion years from now. #astrophoto

The reddening of the Sun by smoke happens the same way light from distant stars is also reddened. The intervening dust (and smoke) preferentially scatter away bluer light leaving mostly red to make it to our eyes.

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.

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.

Messier 101 is a galaxy in Ursa Major. It is about 22 million light years from Earth. Image from last Saturday. 13 minutes L, 5 minutes each R, G and B. 0.2m f3.9 telescope.

Stars that are fusing hydrogen into helium fall along the line that goes from upper left to bottom right on the HR Diagram. This is known as the main sequence. Once the hydrogen in their core is spent, stars evolve up and to the right of the diagram.

Many planetary nebula, such as M 2-9 shown here in this Hubble image, are bipolar, that is have two lobes to each side of the central star. We don't have a clear idea on why this happens. https://octodon.social/media/lnQC6wZJSj9ExCE8yM4

The planet Uranus hot off the telescope. RGB image, 3 seconds each filter. 0.2m f3.9 Newtonian telescope with 2.5x barlow lens. https://octodon.social/media/jO_dMn3iqEQtESZmmvw