Juno at Opposition in 2009

Juno will be in Pisces when it brightens to magnitude 9.5 early in July 2009 and will still be moving in an easterly direction. It reaches a stationary point on August 15 after which Juno will start moving in a retrograde sense to the west, caused by the Earth beginning to overtake the slower moving asteroid. At the same time it will have a considerable southerly component in its motion, crossing the celestial equator into the southern hemisphere on September 2.

The asteroid is at opposition on September 22 when it will be at its brightest, magnitude 7.6. At the same time it will be less than 5° from Uranus which will be brighter at magnitude 5.7. The two are closest at the end of September, with a separation of 4.5° The position of Uranus on September 22 is marked on the chart. Four days after being at opposition, Juno will cross into Aquarius

After opposition Juno will continue to move in a south westerly direction through the stars until it reaches its second stationary point on October 31 after which it starts moving forward in an easterly direction again. Some two weeks later Juno is at its furthest south and then begins to move back to the north.

At the beginning of December Juno crosses into Cetus. It is not until the end of January that it finally fades back to magnitude 9.5.

The distance of Juno from the Sun varies between 1.99 and 3.35 AU, so that at the most favourable oppositions the asteroid is about 1.00 AU from the Earth. At the poorest oppositions it will be well over twice this distance. In 2009 the closest approach of Juno to the Earth will be 1.20 AU, when the asteroid is 2.21 AU from the Sun.

Juno is one of the larger asteroids with a diameter of 234 km. Its orbital period is 4.37 years, the orbit being inclined at 13.0° to the ecliptic. It was discovered in 1804 on September 1 by K Harding at Lillienthal in Germany. Opposition in 1804 was a couple of days later than it will be in 2009, so the asteroid was in a similar part of the sky at discovery to this coming opposition.