No, the Earth's core is not brighter than our Sun. The Sun is an incredibly powerful and luminous star, while the Earth's core is a region deep within the planet. The Sun's brightness is due to the immense amount of energy generated by nuclear fusion in its core, which produces intense light and heat.
The Earth's core, on the other hand, is primarily composed of solid iron and nickel and is not a source of light or heat on the same scale as the Sun. The core's temperature is estimated to be around 5,000 to 6,000 degrees Celsius (9,000 to 11,000 degrees Fahrenheit), which is hot compared to surface temperatures but significantly cooler than the Sun's core temperature of about 15 million degrees Celsius (27 million degrees Fahrenheit).
While the Earth's core does generate heat, it is not visible from the surface, and its brightness is negligible compared to the Sun. The Sun's energy output is what makes it the primary source of light and heat for our solar system.