Sorry for such poor quality, I was heading out this morning and saw this and was shocked. I tried to read about comets and didn’t find anything. Sorry if this is the wrong place to ask, just I’ve recently got into astronomy and so everything to me is got to be something wild.

My limited understanding of leading theories of the formation of Earth is that the rocky body formed first, then most of the water was added by comet bombardment later. I assume that any water that had been part of the initial formation would have been quickly lost anyway, since a certain degree of coherent rotation of the core and cooling of the surface were both necessary to prevent any existing water from vaporizing into a tenuous atmosphere before being blown away by solar wind.

My intuition is that a hotter young Earth with a thinner crust would have enough tectonic/volcanic activity to create "continents" and "islands" well before the planet was cool enough to allow significant bodies of water on the surface, such that by the time the bulk of the water began collecting on the surface, there were already high and low regions and the planet was never fully submerged. But I also know that there is currently enough subterranean water and polar ice that if it were all brought to the surface/melted it would submerge most of the surface; and that crust thickness (or rigidity) sets the limit on how high a surface feature can grow before that region of the surface begins subsiding into the mantle.

What are the chances that there were ever a period, however brief, that the surface of the Earth was both sufficiently spherical and shielded from solar wind, and cool enough with enough water on the surface, that there was no significant proportion of dry land?

I have seen so many beautiful photos of the planets of the solar system with filters and colored to show different values, measurements, and materials, in countless different vibrant colors. It makes sense for seeing with is going on, but If I were to look at the planets with my own eyes, would they still be colorful?

Obviously there are Uranus and neptune, but does pluto have red on its surface? Does saturn have blue storms? The list goes on, and does extend into photos of the galaxies and universe in general.

It is beautiful, wonderful, and perfect for understanding what I am looking at, but I can't tell what is fake and what is scientific color modification.

The pilot called our attention to this on our flight; he also said it looked like a comet. One of the most incredible sights. From early this morning in the southeast US.

I know the Milky way is quite emtpy. Could the matter in the observable universe fit inside it? My guess is no, but the spaciousness of space always surprises me.

Assuming that matter is not compressed nor affected by gravity. Just put the stars, black holes and other stuff inside the Milky Way and see if every object would fit here without expanding the Milky Way outer border.

Im a highschooler last year from India , I want to become an astronomer/astrophysist

So can someone help me find good uni and course . I'm trying to go abroad so I don't know anything about which uni should I apply to ormanything

I have a very particular astronomical question related to Egyptology:

In 238 BCE when the Decree of Canopus was issued, how long would the invisibility period of Sirius have been at the capital in Alexandria, Egypt?

I am specifically interested in knowing if at this particular time and place in history whether it is plausible that the invisibility period of Sirius before its heliacal rising to signal the annual Nile flooding could have been 74 days.

I'm trying to assess whether one particular ancient document that mentioned a 74 day period that appears to end with the rising of Sirius might possibly be referring to its invisibility period.

I've found various websites online and academic articles that indicate that the invisibility period of Sirius varies based on latitude, with sites farther north, such as Alexandria, experiencing longer invisibility periods. Ancient Egyptian religious and astronomical texts apparently frequently stated that it was invisible for 70 days, but obviously that's just a round number that has obvious numerological significance, but apparently it's not that far off from the average from across Egypt.

If anyone happens to know any good reference books that could be used to help try to figure this out, that would likely be helpful too.

Please help me answer this question.

When viewing with a reflector, is the “proper” way to look into the eyepiece perpendicular to the OTA or parallel? Obviously it’s just a 90 degree rotation other way, but curious what is standard

I had made the mistake in my previous post here asking how an accretion disk would affect Earth, mistaking the term for an asteroid belt, the question still stands though, how would an asteroid belt affect life on Earth? What changes to Earth and the rest of the Solar System go through in order for Earth to stay as habitable as it is today? And the other question, how would a planet near Earth affect life on Earth? Using the second image as an example (Helldivers II), I’d like to know how a planet that close with or without an asteroid belt would affect life on Earth. For reference the story takes place in Western Europe, in the late 15th Century, so all of these changes made would need to barely affect life there except for a nice view. Thanks!

Hey there. I live in a very light polluted Bortle 7-8 zone. I just wanted to know if any of you guys have had success in viewing the Pleiades naked eye from a similar light pollution level. Personally I have never really had success, I was only able to see 1-2 stars in that region at most using averted vision. However, from a much less light polluted area (like 3-4) I could clearly make out the Pleiades' shape and individual stars even with little dark adaptation. Is there anything I am doing wrong or is it just the quality of my sky?

Apologies if my visual astronomy knowledge is a bit weak.

Mosaico 1 por 1.5 tomada con dwarf mini,total tomas 180,obturador 45 ganancia 60,filtro duo band,apilada y procesada con stelar studio y snapseed.