40661

40661 is a minor planet in the asteroid belt, located between the orbits of Mars and Jupiter. It was discovered on October 1, 1999, by the Lincoln Near-Earth Asteroid Research (LINEAR) project, a collaborative effort between the United States Air Force, NASA, and the Massachusetts Institute of Technology. The asteroid is named after the year of its discovery, 40661.

40661 has an estimated diameter of about 1.5 kilometers and orbits the Sun with a semi-major axis of approximately 2.5 astronomical units (AU). Its orbital period is roughly 3.9 Earth years. The asteroid's orbit is inclined at an angle of about 15 degrees to the ecliptic plane, and its eccentricity is relatively low, indicating a nearly circular orbit.

The spectral classification of 40661 is S-type, which suggests that it is composed primarily of silicate materials. This classification is based on its reflectance spectrum, which is characteristic of stony asteroids. The surface of 40661 is likely covered in a mixture of silicates and metals, similar to many other asteroids in the inner asteroid belt.

40661 is not considered a near-Earth object (NEO) because its orbit does not bring it close to Earth's path. However, its orbit occasionally brings it within the orbits of Mars and the other inner planets, making it a member of the Apollo group of asteroids. Despite its relatively small size, 40661 is an important object of study for astronomers, as it provides insights into the composition and dynamics of the asteroid belt.