How do we know the Earth axis is tilted?

All you really need to estimate the tilt of Earth’s axis is a carefully positioned pole. Ancient calculations of the axial tilt were made by measuring the length of a shadow cast by a gnomon (a vertical pole) during summer and winter solstice (the longest and shortest days of the year).Click to see full answer. Consequently, how do we know the Earth is tilted 23.5 degrees?Instead, Earth has seasons because our planet’s axis of rotation is tilted at an angle of 23.5 degrees relative to our orbital plane – the plane of Earth’s orbit around the sun. The tilt in the axis of the Earth is called its obliquity by scientists. Over the course of a year, the angle of tilt does not vary.Additionally, how do we know the Earth is on an axis? Earth’s orbital plane is known as the ecliptic plane, and Earth’s tilt is known to astronomers as the obliquity of the ecliptic, being the angle between the ecliptic and the celestial equator on the celestial sphere. It is denoted by the Greek letter ε. Earth currently has an axial tilt of about 23.44°. Moreover, how the Earth is tilted on its axis? Today, the Earth’s axis is tilted 23.5 degrees from the plane of its orbit around the sun. But this tilt changes. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5 degrees. Because this tilt changes, the seasons as we know them can become exaggerated.What happens if Earth’s axis is not tilted?If the Earth weren’t tilted on its axis, there would be no seasons. And humanity would suffer. When a Mars-size object collided with Earth 4.5 billion years ago, it knocked off a chunk that would become the moon. It also tilted Earth sideways a bit, so that our planet now orbits the sun on a slant.