Astronomy and Celestial Phenomena

The lunar cycle from one new moon to the next is approximately 29.5 days. If a new moon occurs on April 1st, the next one will occur about 29 to 30 days later, which is April 30th.

The Sun appears to move across the sky due to Earth's rotation. It rises in the east and sets in the west; therefore, seeing the sun in the western sky indicates that it is setting.

Halley's comet is a short-period comet that orbits the sun every 75 to 76 years. It is the only short-period comet that is regularly visible to the naked eye from Earth.

Melatonin is a hormone produced by the pineal gland that helps regulate the sleep-wake cycle, typically increasing in the evening to promote sleep.

In the Northern Hemisphere, December marks the winter solstice, when the sun is at its lowest point in the sky. This results in the least amount of direct sunlight compared to other months.

In the Northern Hemisphere, June marks the summer solstice, when the sun reaches its highest point in the sky. This results in the most direct sunlight.

Night time is caused by the rotation of the Earth, which turns a location away from the sun. The moon reflects sunlight but does not cause the phenomenon of night.

During the equinoxes in fall and spring, the sun's rays are directed most intensely at the equator, resulting in roughly equal day and night lengths globally.

When it is summer in the Southern Hemisphere, that half of the Earth is tilted toward the sun, causing the sun's direct rays to hit below the equator.

When it is summer in the Northern Hemisphere, the Earth's tilt causes the Northern Hemisphere to lean toward the sun, so the direct rays hit above the equator.

Because the Earth is tilted, the sun's rays hit different latitudes at different angles throughout the year, causing uneven heating and the change of seasons.

Seasons are primarily caused by the 23.5-degree tilt of the Earth's axis as it orbits the sun, which changes the angle and duration of sunlight received by different hemispheres.

Day and night occur because the Earth rotates on its axis, exposing different parts of the planet to the sun's light at different times.

After the full moon, the moon begins waning (shrinking). The waning gibbous phase comes after the full moon as the illuminated portion decreases toward the last quarter. The options 'New moon' and 'Waxing gibbous' are incorrect because waxing means growing. Option D has a typo (wanning instead of waning) but is the correct phase.

The lunar cycle is approximately 29.5 days. A full moon occurs roughly halfway through the cycle, about 14 to 15 days after a new moon.