A chalazion is a small bump that appears on your eyelid because of a blocked oil gland.It can develop on the lower or upper eyelid, and it often disappears without treatment in about one month. chalazion is a small bump that appears on your eyelid because of a blocked oil gland.
Artist's conception of a white dwarf accreting hydrogen from a larger companion. A nova (plural novae or novas) is a cataclysmic nuclear explosion on a white dwarf, which causes a sudden brightening of the star.Novae are not to be confused with other brightening phenomena such as supernovae or luminous red novae.he recurrence interval for a nova is less dependent on the white dwarf's accretion rate than on its mass; with their powerful gravity, massive white dwarfs require less accretion to fuel an outburst than lower-mass ones.
Atoms consist of electrons [electrons: Sub-atomic particles, with a negative charge and a negligible mass relative to protons and neutrons. ] surrounding a nucleus [nucleus: The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom.] containing protons protons: Sub-atomic particles with a positive charge and a relative mass of 1. and neutrons neutrons: Uncharged sub-atomic particles, with a mass of 1 relative to a proton.t contains protons and neutrons, and has most of the mass of the atom. ] containing protons protons: Sub-atomic particles with a positive charge and a relative mass of 1. and neutrons neutrons: Uncharged sub-atomic particles, with a mass of 1 relative to a proton.