Njord is asteroid #4213 and also known as 1987 ST₄. Njord was discovered by the Danish astronomer Poul B. Jensen at Brorfelde. Njord is a common Main Belt Asteroid.

Njord is named after the Norse god Njörðr. According to Wikipedia, where it quotes the official naming citation, is Njörðr the god of winds, navigation and prosperity; besides this he shall be a low-god (vanr). But this isn’t correct. Njörðr gets often confused with the fertility goddess Nerthus, who is found in the sky as asteroid #601. Njörðr is temporarily the husband of the goddess Skaði, who most likely lend her name to Scandinavia. Skaði was granted the right to choose a husband in Asgard, although under the condition that she would choose only by his feet. Asgard is where the high-gods live, so Njörðr is more likely a high-god (áss). Skaði and Njörðr lived alternating nine days in the mountains and nine days at the sea because Njörðr is the god of the sea! So navigation is correct, but he is the god of seas and the ocean. Njörðr is the Norse version of the Roman Neptune and the Greek Poseidon, but more like Poseidon because Njörðr is the father of Freyja and Freyr. Njörðr found the howling of the wolves in the mountains unnerving. Skaði found the shrieking of the sea-gulls unbearable. So Skaði moved to the palace Þrymheimr, which is one of the twelve palaces of Asgard, but used to be the palace of her father, the titan (or jötunn) Thiazi, hence also believed to be located in Jötunheimr.

Among the deities, that are correctly associated with Njord, is only Freyja represented in the sky too. So these two asteroids can hint to a father-daughter relationship in synastries. Njord alone is the Norse counterpart of Neptune and Poseidon. In such cases the differences between the mythologies have to be examined. Norse mythology uses to be in a middle position between Greek and Roman mythology because much guessing is involved in reconstructing the Norse mythology. So Njord is a father unlike Neptune, but also doesn’t try to rival Zeus unlike Poseidon. Njord maintains a middle position between the extremes. This is an additional reason for looking to Njord as the god of navigation. So this can be accepted as his main trait and main subject.