has he authored any books?
Yes - Critique of Pure Reason, Allgemeine Naturgeschichte und Theorie des Himmels
Critique of Pure Reason
The Critique of Pure Reason (; 1781; second edition 1787) is a book by the German philosopher Immanuel Kant, in which the author seeks to determine the limits and scope of metaphysics. Also referred to as Kant's "First Critique", it was followed by the "Critique of Practical Reason" (1788) and the "Critique of Judgment" (1790). In the preface to the first edition, Kant explains that by a "critique of pure reason" he means a critique "of the faculty of reason in general, in respect of all knowledge after which it may strive "independently of all experience"" and that he aims to reach a decision about "the possibility or impossibility of metaphysics."

who propounded the nebular hypothesis for the origin of the earth Immanuel Kant what does this hypothesis state? It suggests that the Solar System formed from gas and dust orbiting the Sun. what are the different types of planets formed out of it? Moon, Mars who is the person mentioned above? A German philosopher and one of the central Enlightenment thinkers.
wiki:4707038
Critique of Pure Reason [SEP] Introduction
A proposition is necessary if it could not possibly be false, and so cannot be denied without contradiction. A proposition is universal if it is true in all cases, and so does not admit of any exceptions. Knowledge gained "a posteriori" through the senses, Kant argues, never imparts absolute necessity and universality, because it is always possible that we might encounter an exception. Kant further elaborates on the distinction between "analytic" and "synthetic" judgments. A proposition is analytic if the content of the "predicate-concept" of the proposition is already contained within the "subject-concept" of that proposition. For example, Kant considers the proposition "All bodies are extended" analytic, since the predicate-concept ('extended') is already contained within—or "thought in"—the subject-concept of the sentence ('body').