Minor-planet moon Herculina does not have a significant satellite. There were other similar reports of asteroids having companions (usually referred to as satellites) in the following years. Also, a letter in "Sky & Telescope" magazine at this time pointed to apparently simultaneous impact craters on Earth (for example, the Clearwater Lakes in Quebec), suggesting that these craters were caused by pairs of gravitationally-bound objects. In 1993, the first asteroid moon was confirmed when the Galileo probe discovered the small Dactyl orbiting 243 Ida in the asteroid belt. The second was discovered around 45 Eugenia in 1998. In 2001, 617 Patroclus and its
Craters of the Moon National Monument and Preserve of open rift cracks in the world, including the deepest known on Earth at . There are excellent examples of almost every variety of basaltic lava, as well as tree molds (cavities left by lava-incinerated trees), lava tubes (a type of cave), and many other volcanic features. Craters of the Moon is in south-central Idaho, midway between Boise and Yellowstone National Park. The lava field reaches southeastward from the Pioneer Mountains. Combined U.S. Highway 20–26–93 cuts through the northwestern part of the monument and provides access to it. However, the rugged landscape of the monument itself remains remote and undeveloped,