How do pigeons sense Earth's magnetic field? Scientists say they’ve solved the mystery.

overcast (adj)

covered with clouds; not bright

subtle (adj)

not very obvious or easy to notice

resolve (v)

to find an acceptable solution to a problem or difficulty

cue (n)

(to V) an action or event that is a signal for somebody to do something

substantiate (v)

to provide information or evidence to prove that something is true

sheath (n)

any layer that covers and fits closely over something for protection

perceive (v)

to notice or become aware of something

plausible (adj)

(of an excuse or explanation) reasonable and likely to be true

indeed (adv)

used to emphasize a positive statement or answer

house (v)

to give a person or animal a place to live, or to provide space for something

decipher (v)

to succeed in finding the meaning of something that is difficult to read or understand

undulation (n)

a smooth, curving shape or movement like a series of waves

appear toV (v)

to give the impression of being or doing something

(be) embedded in st

to fix something in a substance or solid object

churn (v)

to move around violently

churn st into st

st is moved around violently until it changes into another

cosmic (adj)

connected with the whole universe

captive (adj)

kept as a prisoner or in a space that you cannot get out of; unable to escape

penetrate (v)

to go into or through something

dodge (v)

to move quickly and suddenly to one side in order to avoid somebody/something