How do we know the Centre of the earth is hot?

The bottom line here is simply that a large part of the interior of the planet (the outer core) is composed of somewhat impure molten iron alloy. The melting temperature of iron under deep-earth conditions is high, thus providing prima facie evidence that the deep earth is quite hot.

Which instrument is used to measure the temperature of the earth?

thermometer
A thermometer is an instrument that measures temperature.

How do we know how hot the core of the Sun is?

The photosphere, or visible surface of the Sun, typically measures up to 10,000 F (5,540 C). This means that we can determine the effective temperature of the Sun by measuring the amount of light it emits at each wavelength and comparing the resulting spectrum we see to models.

How do we know what the Earth’s core is made of?

Information about Earth’s core mostly comes from analysis of seismic waves and Earth’s magnetic field. The inner core is believed to be composed of an iron–nickel alloy with some other elements.

How do we know the core is solid?

Seismic waves traveling through the earth refract for the same reason that light refracts when entering different substances (e.g. air, water). The inner core has a different density from the outer core, and this difference in density tells us that it is solid.

How do we know the earths core is liquid?

The seismic waves released by earthquakes provide scientists with several forms of measurable evidence that supports the idea of the Earth’s outer core being liquid. Two particular types of waves, compressional waves and shear waves — known commonly as P-waves and S-waves, respectively, provide direct evidence.

How does a thermometer measure temperature?

A thermometer measures temperature through a glass tube sealed with mercury that expands or contracts as the temperature rises or falls. As temperatures rise, the mercury-filled bulb expands into the capillary tube. Its rate of expansion is calibrated on the glass scale.

Do we know if the Earth has a core?

There are no samples of Earth’s core accessible for direct measurement, as there are for Earth’s mantle. Information about Earth’s core mostly comes from analysis of seismic waves and Earth’s magnetic field. The inner core is believed to be composed of an iron–nickel alloy with some other elements.