The warning comes days before she left her duties as secretary general of the International Astronomical Union (UAI), a position to which she was elected in August 2018, for a three-year term.
The astronomer, who took stock and pointed out challenges for astronomy, leaves her post on 26 August, but will continue as an advisor to the UAI for another three years, being able to participate in the organization's decisions without being able to vote.
Teresa Lago highlighted as a "problem" because of the "polluting effect" of "thousands of microsatellites" on the night "sky quality".
In her point of view, despite being "extremely important for communication", these small satellites are limiting astronomical observations, in particular that of very distant celestial bodies, which have a weaker luminosity.
"Our telescopes spend their lives recording the passage of microsatellites because they are much brighter than distant objects", she said, noting that the UAI is "trying to influence the builders" so that "astronomy can continue" in all wavelengths of light.
One of the solutions is to put "covers on microsatellites" to reduce their visibility from Earth.
In addition, the UAI has been trying to convince countries to adopt "more conscious" street lighting that does not overshadow the view of the sky.
Teresa Lago considers that astronomy plays "an important role" in mobilizing the urgency of combating the effects of climate change, highlighting the sensitivity of astronomers, due to the work they do, for "the uniqueness of the Earth, for the difficulty in finding a Earth 'two' or for the near impossibility of getting an Earth 'two' or getting there".
"There is no Earth B," she warned.
The Covid-19 pandemic, which led the UAI to postpone "many scientific meetings", to hold work meetings at a distance and to suspend the activities of the training schools for young astronomers, could be, according to Teresa Lago, "a crucial moment to have a much more visible and much more influential action."
"We don't have competences in the Earth's climate area, but UAI members are concerned and sensitive to the urgency of doing something", she stressed, adding that "when you work with space, when you see the Earth as just a tiny planet, there are no borders, no races, no separations".
The International Astronomical Union was founded on 28 July, 1919.
Portugal joined the organization in 1924 and is one of 82 countries with a seat in the General Assembly and with the right to vote in the election of the board and in matters such as the plan of activities and the budget.
In addition to "national members", where countries are represented by an institution (in the case of Portugal it is the Portuguese Astronomy Society), the UAI has "individual members", 12,167 active professional astronomers from 92 nations, including 78 Portuguese.
The UAI is the entity that officially recognises the assignment of a name to a celestial body, such as a planet, an asteroid or a constellation, and defines the fundamental physical and astronomical constants and astronomical nomenclature.
Scientific research, communication with the public, education, training and the development of less wealthy regions or countries, based on astronomy, are the "pillars" of the "house" that Teresa Lago felt "the need to tidy up" in her management. She set rules, created a code of conduct, approved a "strategic plan for a decade" and got more women like her to participate in the activities.