The Space & Astronomy Thread

[Lroy]

Here's another one I got with some noctilucent clouds.

 

 

[Pompey Repatriated]

Ms Zorgatt (no idea of proper spelling) at Bellfied primary said you don't get clouds at night. Perhaps you need to send her this picture!

[Shropshire_killie]

Dunno if anyone has read Andrew Chaikins "A man on the moon", a history of the moon landings.

I've got a technical question based on what one of the astronauts said on his way there and have been scratching my head a bit on and off for a long time. The moon is about 25% the size of the earth. So, if things were reversed and we were looking up at the earth from the moons surface I imagine Earth would look pretty big

The astronaut said on their way to the moon, so not actually on the moon itself that "looking down, we could see the Earth and I could cover it with my thumb". I suppose, it depends maybe where he was holding his thumb but the quote stuck in my mind as being a bit odd. 

Ps the book isn't a conspiracy theory narrative and really well worth a read. 

 

 

Edited July 25, 2020 by Shropshire_killie
Added a bit

[Lroy]

18 minutes ago, Shropshire_killie said:

I've got a technical question based on what one of the astronauts said on his way there and have been scratching my head a bit on and off for a long time. The moon is about 25% the size of the earth. So, if things were reversed and we were looking up at the earth from the moons surface I imagine Earth would look pretty big

The astronaut said on their way to the moon, so not actually on the moon itself that "looking down, we could see the Earth and I could cover it with my thumb". I suppose, it depends maybe where he was holding his thumb but the quote stuck in my mind as being a bit odd. 

All depends on how far away you held your hand from your eye. I'd guess, if you were trying to cover the Earth with your thumb, your natural reaction would be to bring your hand closer to your face. That means your thumb will cover larger sections of the sky.

They also probably wouldn't have needed to cover the entire disk. All the missions landed on the near side of the moon during lunar daylight. So for the portions of flight where they would have been far away enough to cover the earth, the earth would have been a crescent or gibbous therefore smaller and easier to cover. 

Here's a photo of the earth from the moon during Apollo 17 to show what I mean. It's only half a circle you need to cover.

[CB]

26 minutes ago, Shropshire_killie said:

Dunno if anyone has read Andrew Chaikins "A man on the moon", a history of the moon landings.

I've got a technical question based on what one of the astronauts said on his way there and have been scratching my head a bit on and off for a long time. The moon is about 25% the size of the earth. So, if things were reversed and we were looking up at the earth from the moons surface I imagine Earth would look pretty big

The astronaut said on their way to the moon, so not actually on the moon itself that "looking down, we could see the Earth and I could cover it with my thumb". I suppose, it depends maybe where he was holding his thumb but the quote stuck in my mind as being a bit odd. 

Ps the book isn't a conspiracy theory narrative and really well worth a read. 

 

 

Think most of them has done it at one point or another. Jim Lovell did it on 8. Coming up the far side of the moon. I think he was the first to do it

Quote

"As we kept going, suddenly on the lunar horizon, coming up, was Earth." He remembers the vivid contrast between the lifeless moon and the vibrant earth. "The moon is nothing but shades of gray and darkness. But the earth—you could see the deep blues of the seas, the whites of the clouds, the salmon pink and brown of the land masses."

He says, "At one point I sighted the earth with my thumb—and my thumb from that distance fit over the entire planet. I realized how insignificant we all are if everything I'd ever known is behind my thumb. But at that moment I don't think the three of us understood the lasting significance of what we were looking at."

https://www.newsweek.com/earth-behind-mans-thumb-96783

[CB]

He was maybe trying to do a lunar version of this:

Did you know that you can measure the distances between objects in the sky with just your hands and fingers?

A handy way to measure distances in the sky.

Our conventional methods of measuring distances between two objects on Earth make very little sense when measuring the vast distances between celestial objects.

Measuring Angles

Because of this, astronomers measure the distance between celestial objects based on the angle they make with an observational point on Earth. Known as angular distances or angular separation, distances are expressed in terms of degrees (°), arc minutes ('), and arc seconds (").

While angular separation primarily describes the apparent distance between celestial objects, as seen from Earth, it can also be used to suggest their actual distance from one another.

Imagining Angles in the Sky

Like our modern-day timekeeping, the angular method is based on a sexagesimal system – a numeral system with 60 as its base. There are 360° in a circle or sphere, each degree is divided into 60' and each arc minute is further divided into 60".

Imagine the sky as a big hollow sphere with the Earth at its center – let’s call this the celestial sphere. This sphere is 360°. If you look above at the sky, you will see only half of the sky i.e. 180° of the celestial sphere. The other half of the celestial sphere is below the horizon and cannot be seen. The point right above you in the sky is the zenith. The zenith is always 90° from the horizon.

A “Handy” Way to Measure Distances

Hold your hand at arm’s length and close one eye.

• Make a fist, with the back of your hand facing you. The width of your fist will approximately be 10 degrees. This means that any two objects that are on the opposite ends of your fist will be 10 degrees apart. The North Star (Polaris) and Dubhe, one of the northern pointers of the Big Dipper are 3 fists apart. This means that angular distance or angular separation between the two stars is 30°.
• Open up your fist, stretch your little finger and thumb as far as you can and curl down the rest of your fingers. The tip of your little finger and your thumb will span about 25°. The Big Dipper spans around 25°.
• The tip-to-tip span between your index finger and your little finger is 15°.
• Your three middle fingers will span about 5°.
• Your little finger at an arms length is about 1° wide.

It is important to note that such measurements are approximate – not everyone has the same sized hand.

With these simple measuring rules in your hand, you can not only understand basic stargazing jargon but also tell other budding stargazers where to look for a specific celestial object in the sky.

Angular Size

Angular size or angular diameter of a celestial object is the angular separation between opposite edges of the object. The Sun and the Moon are the only objects in the sky whose angular size is visible to the naked eye.

Remember to never look at the Sun directly without any eye protection!

The angular diameter of a full Moon is about 30', while the angular diameter of the Sun is around 32'.

Find Your Latitude

If you are in the Northern Hemisphere, you can use your hands to find your current location’s latitude. To do this, stretch your hands in front of you and measure the angle between the visible horizon and the North Star. This angle is your latitude in degrees.

Unfortunately, there is no bright star equivalent to the North Star in the Southern Hemisphere.

https://www.timeanddate.com/astronomy/measuring-the-sky-by-hand.html

[Shropshire_killie]

Interesting Thank ye fellas. 

[Lroy]

We all been keeping up to date with SpaceX's Mars rocket?

Landing attempts have so far been... less than partially successful. The rest of the flight has gone very well!

 

[gdevoy]

3 minutes ago, TommyJo said:

Do you think the small satellite launch market is overheated or are experts exaggerating?

I think demand for shall satellite launch into low earth orbit has been over estimated by development companies.

[Shropshire_killie]

Came back from Oz today via Knockin after shopping at Aldi. Had a gander at the scope. As you can see it's a bit grubby. No one about and just a dull humming could be heard. 

 

Edited March 4, 2021 by Shropshire_killie
Fixed a bit

[Wrangodog]

Fantastic photos from this young lady.

https://www.bbc.co.uk/news/uk-scotland-south-scotland-56215197

[Shropshire_killie]

[Pompey Repatriated]

On 7/25/2020 at 8:29 AM, Lroy said:

Here's a photo of the earth from the moon during Apollo 17 to show what I mean. It's only half a circle you need to cover.

That's interesting. You don't think of the Earth as not appearing whole from the Moon

[Lroy]

Using a telescope to project the sun on to paper during today's eclipse.

[Lroy]

On 5/26/2016 at 10:32 PM, Lroy said:

SpaceX are going for their 3rd successful landing in a row in a few minutes, landing occurring about 10mins after launch.

6 years to they day after their first landing SpaceX have now landed boosters 100 times. One booster is now up to 12 flights. Only 2 of their 31 flights this year we're on new boosters.

[Lroy]

Its launch day for the James Webb Space Telescope tomorrow from French Guiana. Massively delayed, the mission has about 300 points of failure where any one will cause the loss of mission. Probably the most important rocket launch since Hubble, the JWST should really change astronomy.

[Lroy]

All good so far. Launch and solar array deployment perfect.

[Shropshire_killie]

Been jolly quiet on here, so....

Who owns the Moon?

Been sorting out me paperwork and came across this. Yep, that's right, I own an acre of the Moon! I actually think I own two acres but one of the deeds is missing

[Bonbon19]

51 minutes ago, Shropshire_killie said:

Been jolly quiet on here, so....

Who owns the Moon?

Been sorting out me paperwork and came across this. Yep, that's right, I own an acre of the Moon! I actually think I own two acres but one of the deeds is missing

Hope you evicted those Clangers from your property Shropshire .

[Pompey Repatriated]

Venus, Mars, Jupiter, Saturn were all in vertical alignment in the Southern hemisphere. https://www.dw.com/en/when-four-planets-align-venus-and-jupiter-collide/a-61625441

Last couple nights there's been a  red crescent moon. Unusual in its self as red moons are normally full. But it was also the first time I've noticed the moon set below the horizon. 

[Wullie31]

I'm going to see Brian Cox at the Hydro on 2nd October, just wondered if anyone else in here was heading to it. Should be good, his previous shows have great reviews.

 

[Shropshire_killie]

Seen the size of the Moon tonight!  Never seen it so big and have gawped at it for years. If I was a conspiracy theory type o chap, I'd swear it's getting closer to earth. 

[Lroy]

7 hours ago, Shropshire_killie said:

Seen the size of the Moon tonight!  Never seen it so big and have gawped at it for years. If I was a conspiracy theory type o chap, I'd swear it's getting closer to earth. 

It's not a conspiracy, its just science. The moon doesn't have a circular orbit, it is slightly elongated. The point at which it is closest to Earth is called its perigee and its closest perigee in 2022 is... TODAY! It's also coincidently a full moon which means it's up to 25% brighter than if was at its furthest point, apogee.

[Lroy]

I take it we all saw James Webb Telescope's first colour images? Best of which being this one...

or maybe this one?

Every single dot on this image (apart from the ones with lens flare) is a galaxy of trillions upon trillions of stars. Zoom in, see that tiny wee dot? Galaxy of trillions of stars.

Hubble did take similar, not quite as good photos of the same areas, but took over 10 days to do so when JWST can do it over a few hours.

 

[Shropshire_killie]

3 hours ago, Lroy said:

I take it we all saw James Webb Telescope's first colour images? Best of which being this one...

or maybe this one?

Every single dot on this image (apart from the ones with lens flare) is a galaxy of trillions upon trillions of stars. Zoom in, see that tiny wee dot? Galaxy of trillions of stars.

Hubble did take similar, not quite as good photos of the same areas, but took over 10 days to do so when JWST can do it over a few hours.

 

Absolutely amazing. There's got to be life out there. Cheers for moon info Lroy. Kind of explains why I been feeling a bit weird. My so called friend kindly pointed out that's where the term lunatic comes from and certainly applicable in my case.