# A star is ten light-years away from the earth. Suppose it brightens up suddenly today. After how much time shall we see this change?

1 light-year= distance covered by light in one year.

10 light-years away from the earth glow today, then it will be seen after 10 years.

∴ A star is ten light-years away from the earth. Suppose it brightens up suddenly today. After 10 years time, we shall see this change.