... Sometimes called the Iris Nebula and dutifully cataloged as NGC 7023, this is not the only nebula in the sky to evoke the imagery of flowers. ... Why is the northern half of asteroid Vesta more heavily cratered than the south? ... This unexpected mystery has come to light only in the past few weeks since the robotic Dawn mission became the first spacecraft to orbit the second largest object in the asteroid belt between Mars and Jupiter. ... What has the Opportunity rover found on Mars? ...