Is the sky exactly the same in different countries in the northern hemisphere?

[syncmaster913n]

Hello,

Beginner here, no past telescope viewing experience. My question is a general one. I realize that what we see in the sky will differ based on whether one is in the northern or southern hemisphere. But.. is there any different from location to location within the same hemisphere?

So suppose one observer is in Ireland and the other one is in Poland, and both observers point their telescope at the exact same point in the sky at precisely the same time. Assuming both observers are using the exact same (advanced) equipment and have the same viewing experience and abilities, and also that weather conditions and light pollution are exactly the same, is it possible that any of the two observers could see something (or acquire some - any - scientific data) that the other observer would not be able to obtain?

[brantuk]

Nope - it depends on which time zone you're in. Stuff rises in the East and sets in the West - East of us a specific object rises earlier and to the west it comes up later. E.g. Poland will see Orion earlier than England - and America will see it later. Hth

[goodricke1]

Well assuming they are exactly on the same line of latitude yes they will see the same sights, when it comes to very distant objects such as stars, nebulae etc. For a closer object such as the Moon they will see a slight difference in position. And for very close objects such as meteors they will see different manifestations.

Edit: when you say 'at the same time' I am assuming the time zone difference is taken into account.

[vlaiv]

In theory, given that all is exactly the same from two different locations on earth (regardless of hemisphere, could be one observer in south and one in north) - there is just a small window in time for given target that both observers will have exactly the same conditions (and this holds for some areas in the sky). In such conditions in theory they will get no difference in view. But due to earth rotation - observer in Ireland will see the target rising in the sky, while observer in Poland will see it setting. In one instance it will be at same height for both observers. And how high target is in sky has impact on view as well - due to air mass, even if atmospheric conditions are exactly the same. This holds only for targets that not impacted by parallax - distant ones - moon will look different depending on angle being observed from.

[Knighty2112]

In theory if sky conditions are all exactly the same, and equipment too, then yes all images in all three scopes will be exactly the same. The only difference might be that you might have slightly darker sky conditions due to the time difference between the sites, so the site in Poland may have a darker sky to observe with perhaps depending on when the observations might take place, or vice versa.

[mikeyj1]

Hi there,

If there is only a LONGITUDE difference then they will see the same things generally (local horizon conditions excepted), but just at different times, just like the time zone differences and the Sun Rise/Set times.

If there is a LATITUDE   difference (ie further S) then they will see more of the stars that only just come over the horizon at the more northern observer's position.  Spica, in Virgo for instance low in our UK sky in Early morning, (~11deg)  but would be over 40 deg high if you were at a latitude of 31 deg.

Some constellations and stars never set in the Northern Hemisphere (like Polaris and Ursa Minor).  Those that follow close to the Ecliptic, (the apparent path of the Sun) will be visible to almost all, just as the Sun rises and sets to almost all.  That's caused by the tilt of the spinning axis of earth at 23.5 deg

it was interesting to be in Australia recently and see that Orion is also prominent in their SUMMER sky whereas it is prominent in our WINTER sky

hope that helps

 

Mike 

 

[ollypenrice]

The concept of sidereal time becomes helpful here. Sidereal time is measured against the position of the stars rather than the sun. The sideeal day is just under 4 minutes shorter than the day measured against the sun. Any object has a set of co-ordinates defined by right ascension and declination. Any and every object reaches its highest point in the sky when its coordinates in right ascension are the same as its local sidereal time. The higher an object is, the better the view. But if you move north or south the object changes height either for better or for worse.

Olly

[noah4x4]

If you set daylight saving time = yes in the northern hemisphere  then currently all your gotos will be 15° out (360°/24 hours). Hence "zone" from UT (GMT) is also important.  Oddities occur like Madrid where UT is the same as London, but it follows +1 European time and may also require a DST adjustment. Causes more alignment use errors than any other.