Cratering gives us much information. Surfaces with more cratering are older than surfaces with less cratering for example. Cratering also gives us an idea of how geologically active a world is. Less craters, more likely to have been or be geologically active.

I've been indexed at the Harvard ADS! SQUEEEEE!
Though they have the wrong institutional affiliation...

The earliest in history we can look back (with electromagnetic radiation that is) is about 380000 years after the Big Bang because the universe was too hot before this for light to get around. This Planck image shows what the surface of this was - seen as the CMB.

Sunspots can be quite large. These ones from 07 July 2014 are larger than the Earth (dot indicated is the size of Earth to scale).
Stars also have similar spots and their appearance on the star makes it harder to locate exoplanets.

Open clusters, such as M36 (shown), are important in our understanding of stellar evolution. Since the stars in the cluster were all formed at more or less the same time, we can see how their different masses evolve through time.

One way that planetary nebula are discovered is by taking images through broad band filters then comparing them to narrow band line filters. The PN will dim less than the stars. This can be seen by comparing the RGB image of NGC6058 (left) to the narrow H Alpha (right).

M20 - The Trifid Nebula - is an HII star formation region in Sagittarius. It is about 5500 ly away from Earth. Observations a various wavelengths (IR, visual, X-Ray) have identified stars at many stages of formation inside the nebula.

Carbon dioxide levels as measured in Calgary. Day of the week, hour of the weekdays, and hour of the weekend averages. Some interesting patterns.

M11 - the Wild Duck cluster - is an open cluster in the constellation of Scutum. It is about 6100 ly from Earth and contains over 2000 stars. It's age is between 200 million and 250 million years.

M87 is a massive elliptical galaxy in the constellation of Virgo. It is about 54 Mly away. It could be upwards of 200 times the mass of our own galaxy and is one of the more massive objects local to us.

My child is off on his first Navy League Cadet campout for the weekend. Let the peace and quiet commence...

M57 - the Ring Nebula - is a planetary nebula in the constellation Lyra. Planetary nebula have nothing to do with planets. They picked up that name from William Herschel who had just discovered Uranus and thought they looked similar.

‪There’s an evil amount of carbon dioxide outside...‬

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Octodon is a nice general purpose instance. more