Astronomers have pieced together a massive mosaic of the nearby Triangulum Galaxy from images taken by the Hubble Space Telescope. The Vast spiral galaxy is located just three million light-years from Earth, and can sometimes even be seen by the naked eye as a faint, nebulous object on a clear night.

The Triangulum Galaxy, also known as Messier 33, belongs to the Local Group – a gravitationally bound collection of more than 50 galaxies that includes the Milky Way and the nearby Andromeda Galaxy.

Whilst both are spiral galaxies, Messier 33 differs from the Milky Way in many ways. For one, the Triangulum Galaxy is much smaller, with a diameter of just 60,000 light-years compared to the Milky Way's 100,000. Beyond size there are structural differences.

The Milky Way is thought to have a pronounced central bar running through its heart, along with a central bulge. Messier 33 boasts neither of these features. What it does have is an abundance of dust and gas, from which generations of new stars are being born at a rate of roughly one solar mass every two years.

These enormous stellar nurseries rank among the largest and brightest in the Local Cluster, shining with the light of ionized hydrogen. It was the presence of these active star forming regions that led astronomers to target Messier 33 with the Hubble telescope.

The latest vista of the Triangulum Galaxy is stitched together from 54 separate images taken by the Hubble's Advanced Camera for Surveys. The mosaic measures 34,372 x 19,345 pixels, making it the second largest mosaic ever compiled from Hubble data with a total pixel count of 665 million pixels. The top spot goes to a 2015 image of the Andromeda Galaxy, which was comprised of a staggering 1.5 billion pixels.

The new mosaic covers the central section, and inner spiral arms of Messier 33. Within its scope lies roughly 10 – 15 million individual stars, along with numerous star clusters and bright nebulae. Astronomers hope that the new image, along with previous surveys taken of the Andromeda and Milky Way galaxies, will help them gain a deeper understanding of stellar evolution in the Local Group and beyond.

A zoomable version of the mosaic can be accessed via ESA's Hubble website.

Scroll down to watch a video moving in on the Triangulum Galaxy from the perspective of Earth.

Source: ESA

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