Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.
9/20/2016 Ghirapur Orrery’s first ability allows a player to play an additional land during their main phase. Doing so follows the normal timing rules for playing lands.
9/20/2016 Ghirapur Orrery’s first ability is cumulative if more than one is on the battlefield.
9/20/2016 No player may take actions in a turn before Ghirapur Orrery’s second ability checks to see if it should trigger. If the player whose turn it is has any cards in hand, it won’t trigger.
9/20/2016 If the player has any cards in hand as Ghirapur Orrery’s second ability resolves, the ability does nothing. Notably, a second Ghirapur Orrery won’t have a player draw another three cards unless the player empties their hand after resolving the first one’s trigger.
9/20/2016 The draw step is after the upkeep step, so drawing a card as a turn-based action won’t affect whether Ghirapur Orrery’s second ability triggers.
9/20/2016 In a Two-Headed Giant game, Ghirapur Orrery’s second ability triggers for each player on a team separately. If one player has cards in hand, it can still trigger for the other player.