THE Milky Way has been obscuring a vast blob of dark primordial hydrogen in
our backyard, astronomers said last week at a meeting in New Mexico. The Galaxy
blocks our view of more distant objects, but is nearly transparent at the
21-centimetre wavelength used by the Parkes radio telescope in Australia. This
has revealed hundreds of small or dim galaxies, and a cloud containing 20
million solar masses of hydrogen only 10 million light years away.
The cloud is big enough to form a dwarf galaxy if it collapsed. “We may be
seeing the building blocks for galaxies,” says Rachel…
