Near-Earth Objects
An NEO's orbit takes it within 1.3 AU of the Sun. The largest known NEO is over 40 km in diameter, but astronomers have found thousands of NEOs with diameters larger than 1 km. Anything smaller is too hard to see.
Comets
Comets are large balls of rock, ice, dust and gases. They contain frozen leftovers from the early Solar System. Material that is about 4,600 million years old!
Astronomers have discovered about 4,000 comets in our Solar System so far. Most comets come from beyond Pluto, in the Oort Cloud. We have not fully explored these dark and distant parts of space yet. So there are probably billions more comets out there!
Maria Mitchell
Occupation
Astronomer, Educator, Librarian
Year born
1818
Research Areas
Comets, Solar Eclipse, Planets, Double Stars, Nebulae
- Early Life
Maria was born in Nantucket, USA. Her family made sure that all 10 of their children were well-educated, the girls and the boys. Maria also read about lots of topics in the local library, where her mother worked. Her father was a teacher and his hobby was astronomy.
Caroline Herschel
Occupation
Astronomer
Year born
1750
Research Areas
Comets, Nebulae, Star Clusters
- Early Life
Caroline was born in Hanover, Germany. Her father had been an army musician, but had to retire due to ill health before Caroline was born. Caroline herself had typhus when she was 10 years old. The illness stunted her growth at 4 foot 3 inches and left her with vision loss in one eye.
Caroline's mother thought she should find work as a house servant when she was older. She learned to read and write, but she did not attend school. However, her father sometimes tutored her or included her in the lessons he gave to her brothers.
Edmond Halley
Occupation
Astronomer, Mathematician
Year born
1656
Research Areas
Comets, Transits, Stars, Maths, Geophysics
Make a Comet on a Stick
Comets are large balls of ice, rock and dust but you can think of them as large dirty snowballs that travel through the Solar System.
Gerard Kuiper
Occupation: Astronomer & Planetary Scientist
Year born: 1905
Research Areas: Atmospheres and Moons