A Japanese spacecraft has finally made it to Venus after circling the sun for five years on an unscheduled detour.

The Venus Climate Orbiter Akatsuki entered orbit around Venus at 8:51 a.m. Japan Standard Time Monday (6 p.m. Sunday ET), the Japan Aerospace Exploration Agency (JAXA) announced Monday.

"The orbiter is now in good health," it added in a news release.

The spacecraft launched May 21, 2010, and was supposed to arrive at Venus on Dec. 7 of that year, but failed to inject itself into orbit around Earth's nearest neighbouring planet.

It has been circling the sun ever since, but JAXA planned to have another go at entering Venus's orbit when it passed close by this year.

The spacecraft is designed to take close-up photos of Venus and observe weather conditions such as the fierce winds that blast across the planet's surface at 100 metres a second or 60 times the speed at which Venus rotates.

"This phenomenon remains the biggest mystery of Venus, as it cannot be explained meteorologically," JAXA says.

It will use infrared light to peer through Venus's thick clouds at the surface, observe the particles escaping from Venus's atmosphere into space and confirm whether Venus has active volcanoes and thunder.

Venus was studied by numerous Soviet and NASA spacecraft in the 1970s and 1980s, but has received far fewer visitors in recent years.

Before Akatsuki, the last spacecraft to enter orbit around Venus was the European Space Agency's Venus Express, which arrived in 2005 and lost contact with Earth in 2014.