Answer: Some challenges that I could see would be the walls, possibly a moat, tar, and the towers.
Explanation: The wall is obliviously a main problem, trying to get over it or through it is a difficult challenge. The moat (if it has one) means that there is more than likely only one way to get in or out. If it does have tar it means that the attackers are going to be put in a "sticky situation" And finally the towers, they have people at the top shooting arrows down at you, or throwing things at you.
distance to the star Betelgeuse: 640 ly
As we know that

also we know that


So the distance of Betelgeuse = 640 ly

distance to the star VY Canis Majoris: 


distance to the galaxy Large Magellanic Cloud: 49976 pc


now we have


distance to Neptune at the farthest: 4.7 billion km

now the order of distance from least to greatest is as following
1. distance to Neptune at the farthest
2. distance of Betelgeuse
3. distance to the star VY Canis Majoris
4. distance to the galaxy Large Magellanic Cloud
<span>Because of our perception of the universe from inside the universe, we are unable to see how and towards what the universe is expanding. Also, our understanding of it is further complicated because we are moving as part of the expansion, thus distorting our perception of it.</span>
From the average speed you can fix an equation:
Average speed = distance / time
You know the average speed = 65.1 kg / h, then
65.1 = distance / total time,
where total time is the time traveling plus 22.0 minutes
Call t the time treavelling and pass 22 minutes to hours:
65.1 = distance / [t + 22/60] ==> distance = [t + 22/60]*65.1
From the constant speed, you can fix a second equation
Constant speed = distance / time traveling
94.5 = distance / t ==> distance = 94.5 * t
The distance is the same in both equations, then you have:
[t +22/60] * 65.1 = 94.5 t
Now you can solve for t.
65.1t + 22*65.1/60 = 94.5t
94.5t - 65.1t = 22*65.1/60
29.4t = 23.87
t = 23.87 / 29.4
t = 0.812 hours
distance = 94.5 km/h * 0.812 h = 76.7 km
Answers: 1) 0.81 hours, 2) 76.7 km