Answer:
New moon and Full moon
Explanation:
The phase of the moon refers to the time when the Moon appears to be in a particular shape relative to the position of earth and sun. The different stages of the moon are such as-
It starts initially with the new moon through sequential events which are crescent (waxing), 1st quarter, gibbous (waxing), and further continue with the full moon, gibbous(waning) and last quarter and the cycle repeats again with the new moon.
In the case of a new moon, the moon is not visible because of the exposure of the unlit half of the moon. It takes place when the moon comes in between the Sun and the earth. It is usually marked by the occurrence of a solar eclipse.
The full moon phase refers to the fully exposed, lit part of the moon. It takes place when the moon is oriented towards the opposite end of the earth from the Sun and is often marked by the occurrence of a lunar eclipse.
Thus, the phases of the moon that are directly opposite to one other in terms of both appearance and position are the full moon and the new moon.
