What would the view be list from TRAPPIST-1g, looking back towards TRAPPIST-1? There's a lot of interest with the recent discovery of seven earth sized planets around TRAPPIST-1. I saw this poster, and the NASA video says that in the system you could see a lot of other planets whipping around in their orbits. 

It got me wondering:


Obviously that poster is exaggerated, but how exaggerated? 
What would you actually see with the naked eye, standing on TRAPPIST-1g, and looking back toward the other planets? 
How big would they appear?
What might TRAPPIST-1 look like?
Let's take a look at the star and the planet's characteristics first. We have the star TRAPPIST-1:


$M = 0.082 M_{\odot}$
$R = 0.117 R_{\odot}$


The planets are all roughly in the scale of $0.7 R_{\oplus}$ to $1.2 R_{\oplus}$ with their semi-major axes of:


b: $1.66 \times 10^6 \; \mathrm{km}$
c: $2.88 \times 10^6 \; \mathrm{km}$
d: $3.14 \times 10^6 \; \mathrm{km}$
e: $4.19 \times 10^6 \; \mathrm{km}$
f: $5.57 \times 10^6 \; \mathrm{km}$
g: $6.73 \times 10^6 \; \mathrm{km}$


So if we would stand on the surface of TRAPPIST-1g and look towards the star, we would be at $1/25$ the distance to the star compared to the sun. The star however is roughly $1/8 R_{\odot}$. That would make the star appear about at about $3$ times the diameter compared to our Sun from the Earth.

TRAPPIST-1f would every few days pass TRAPPIST-1g with a closest approach of $1.16 \times 10^6 \; \mathrm{km} \approx 3 \times r_{\mathrm{Earth-Moon}}$ which is roughly three times the distance to the Moon. 

Since $R_{\mathrm{TRAPPIST-1f}} \approx R_{\oplus}$ and $R_{\oplus}/R_{\mathrm{Moon}} = 3.67$ it would seem that TRAPPIST-1f would appear roughly the size of the Moon on closest approach.

The other planets are similar in radius but their distances are $2$ to $5$ times further away and would thus appear smaller by that factor.