Brilliant program and lots of fun. It can do bubbles instead of planets too! Start with an empty universe, turn on bounce (important) and then just add lots of equal sized planets close to each other, but not touching. They just settle into a wobbling ball. Adding new planets is fairly safe, but don't add them too far away or the whole lot gets blown apart. Here's a sample.

zoom 1.00000000000000000000e+00
center (2.71571164577252091021e+01, -2.38608721895672992730e+01)
delta 4.50000000000000011102e-01

body
   pos (6.30267504491734911198e+01, -9.67462299231702971269e+00)
   velocity (-3.07589122909403545059e-01, -2.86976765998950451853e-02)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#05B22D"
   id 266992558

body
   pos (4.92195395748228392563e+01, -5.62922478840120632526e+01)
   velocity (-3.39592704087660679502e-01, 1.25102219071829590114e+00)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#B9ED3C"
   id 148253612

body
   pos (-2.15579519631063565299e+00, -4.56437815718717416757e+01)
   velocity (-3.63263011756724429890e-01, -1.11333162556024745093e+00)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#1CFBF4"
   id 330278895

body
   pos (3.71089179199740044623e+01, -4.04060676139954964015e+01)
   velocity (-6.75375587845302716161e-01, -4.22091634156622874663e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#23F47D"
   id 139125176

body
   pos (2.67956347832535684006e+01, -6.09895027817415069649e+00)
   velocity (-1.89911913457666073346e-02, 1.88426309531988175894e-02)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#A81D40"
   id 701049993

body
   pos (-9.61341265550737666956e+00, -2.46432046290542707823e+01)
   velocity (8.72027926916358220311e-01, -8.12498582306704242306e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#64BC1E"
   id 34397179

body
   pos (4.47537929457907495134e+01, -1.70236119943940593657e+01)
   velocity (-1.99010361206334585038e-02, -1.02331743565878402480e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#F200F9"
   id 215947671

body
   pos (5.22901540180578439099e-01, -1.95460147469716316593e+00)
   velocity (1.41121301395214215901e+00, 4.30377565331800715498e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#E711CC"
   id 220025019

body
   pos (1.78416851043243909203e+01, 1.22297455844657054769e+01)
   velocity (-8.24872858711623857531e-01, 1.85318879758332472063e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#FA957E"
   id 46923669

body
   pos (4.39445931434986434283e+01, 6.40654042400937751012e+00)
   velocity (-4.52997229952179614187e-01, 1.12163925338759784545e+00)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#20BCF4"
   id 903705993

body
   pos (1.06109865826936893285e+01, -1.90310136624819321582e+01)
   velocity (4.78797032872906036527e-01, -3.09694802101768806857e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#793DEE"
   id 147263963

body
   pos (1.61921150202965549170e+01, -3.87958011631139214614e+01)
   velocity (-2.03334702901910607808e-01, -1.03671582797245573349e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#579B52"
   id 211981361

body
   pos (2.34285314305423497672e+01, -5.83642412076537624444e+01)
   velocity (-5.69054822972896376387e-02, -6.03321335509927836327e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#FB7C4B"
   id 1037907476

body
   pos (2.85320847734490428138e+01, -2.47594961149768408859e+01)
   velocity (5.51827997495728306276e-01, -2.28561701230677011276e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#2A8FBE"
   id 594645053

body
   pos (5.71484214496973947917e+01, -3.38617282652426894174e+01)
   velocity (-5.10430433086043258695e-02, 7.17000163679725188715e-01)
   radius 1.50000000000000000000e+01
   mass 3.37500000000000000000e+03
   color "#E0B8E1"
   id 775927549