 When plans were drawn up for a major expansion of the adjacent Royal Ontario Museum in the mid @-@ 1970s , it was initially assumed that the planetarium , then still a comparatively new facility , would be left untouched . As the scope of the expansion increased , it was realized that its north annex would need to be demolished in order to make way for the museum 's need for a wing devoted to curatorial facilities . As a result , a theatre entrance , sound studio , workshop , passenger elevator and a third of the existing gallery area of the planetarium had to go . The remaining gallery area was removed in March 1978 to make space for temporary space to replace the workshop and studio . 
