Listen to part of a lecture in an astronomy class.
Today we're going to talk about the discovery of Neptune, the eighth planet from the sun. The story begins in the early 19th century, when astronomers noticed that Uranus, the seventh planet, wasn't following its predicted orbit exactly. There were slight deviations, or perturbations, that couldn't be explained by the gravitational influence of known planets. Two mathematicians, John Couch Adams in England and Urbain Le Verrier in France, independently calculated the position of an unknown planet that might be causing these irregularities. They both predicted a location in the sky. However, Adams's work was not immediately acted upon by British astronomers, who were slow to search. Le Verrier, meanwhile, sent his prediction to the Berlin Observatory, where Johann Galle observed the planet within one degree of the predicted spot on September 23, 1846. This discovery was a triumph for Newton's law of gravitation and showed the power of mathematical prediction in astronomy. It also led to a bitter controversy between the English and French over who deserved credit.
❓ Pregunta What is the main point of the lecture?
A. A) The discovery of Neptune was based on mathematical predictions of perturbations in Uranus's orbit.
B. B) Astronomers in England and France worked together to find Neptune.
C. C) The discovery of Neptune proved that Newton's law of gravitation was wrong.
D. D) Uranus's orbit was perfectly explained by known planets before Neptune was found.
✅ Respuesta correcta
A) The discovery of Neptune was based on mathematical predictions of perturbations in Uranus's orbit.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word